1992PonFirebird

I bought a Chevy 6.6L 400 small block about a month ago, I have a airesearch turbo charger that I bought a while back brand new and I have a Holley 750cfm vacuum secondary Carb. I want to tear the engine down and build it back up to put in my 1992 Firebird. I wanted to ask what some people's thoughts and opinions are. I want to see what type of Crank I have in the engine first but if it is cast steel I was thinking I would leave that in but put in forged rods, hypereutectic low compression pistons (About 8 to 1 or 9 to 1 compression ratio), and a new intake. I want to do a new camshaft but I don't know what kind I should get. With this set up how much psi could I run? (My turbo can hold up to 35psi of boost but I don't want to run that much I just want to be able to run 12 to 15 in town and 20 on the strip) What type of camshaft do you think I should get? Does anyone have a single turbo set up in there firebird or camaro? If you do what do you have in your engine?

fireturd350

iTrader: (8)

You probably should look at a different piston set. I know some people recommend them even Corky Bell, but IMO Hypereutectic are junk once you start pushing high temps and high pressure (high chance of denotation). They might be okay for low boost with a good tune, but if you're wanting high pressure 10-15 Street and 20 Strip you're going to want a good 4340 Forged Assembly with ARP fasteners.

Before you spend a ton of money on parts and things I would recommend you get the block checked out by a machine shop. It would suck to buy a full assembly just to find you need another block.

Also you'll probably want to get new heads. Aluminum is better for heat dispation. I highly doubt the old springs can hold up to 10 let alone 20.

Is your carb setup for blow thru?

I don't know about swapping the boost pressure between street and strip. I would think it could be done but I don't know if a boost referenced FPR would be enough it might take jet changes. I've seen various setups running like that but they were EFI and could just flip to a saved preset tune to make the fuel map change.

Orr89RocZ

iTrader: (20)

If you put 20 psi thru that block with any kind of decent head cam package and with a proper sized turbo that block may be split in two.

20 psi could be 700-1100 whp depending. Simple setup like afr 195's and 233 deg hyd roller is 700-750 whp on 15 psi in a 400" sbc. You are pushing it....No special forged rotating assembly will help save the block but you should look into forged crank and pistons

1gary

For me I have noticed in myself typing alot negative posts.Kind of sucks because I do really want to promote the builds guys want to do.I think I'm put into this position because most guys don't want to face the fact it costs to go fast.When Orr tells you can't run that kind of boost,you better put on your listening ears.He has yrs of doing this in turbos and knows them well.

The 400's are know for the possibility of thin walls where a mere .030 needs for you to sonic check them for thickness.The siamese bores are know for moving around alot creating sealing issues when used as a serious high performance engine.To find a good core these days is getting hard to find one that isn't cracked.So you must mag the block to insure you have a good one.Don't post you have a running engine.Still needs to be checked.Been there done that.What we have done on a N/A that we where running 9.90 was to fill the block 1/2 way to help stabilize the bores and then with the pistons in hand to fit the bores,bored/honed with torque plates.That is a critical operation on these production 400.It is a must do.Good forged pistons like TRW or Wisco please,forged rods with ARP bolts,as suggested aftermarket aluminum heads with a minimum runner size of 200cc.Now the crank that was production in the 400's is a cast crank.Don't get tangled up in companies trying to play spin words like "cast forged". Cast is cast and good forged cranks are forged.It would be silly to risk everything else with making do with a production cast crank should anything go wrong. For that plan on spending from $800 and up.So what we are talking about is a engine in the range of a easy $5,000 to $7,000.Really what I think Orr was talking was a aftermarket block.I mean by the time you end up screwing around with a O.E.M. block,your better off going the route of a aftermarket block.And there are a number of different options for them with increasing costs.So now to push the kind of boost your talking about the price range jumps to a easy $8,000 to $10,000 for the engine and you haven't touched the driveline or suspension yet.

I did start this by saying I 'm aware of the negative posts I have been making and really want to promote the builds guys want to do.I know this is bench racing at the very best it could be.But I do on some of these posts spend a fair amount of time paying it forward,well really paying it back,for all the guys who have helped me over the yrs.And that is with at the age of 65 very infected arthritic/diabetic nerve damaged hands. So Sir please respect the effort and do take this advise seriously and understand the guys on here who you see have completed their projects have thousands of dollars and yrs invested.

Orr89RocZ

iTrader: (20)

Yup if block sonic checks out and you do a half fill maybe it will live under 15 psi but keep rpms down. It may live. Its like 10 bolt rears, some break some dont under big power.

I know my buddy has been high 9's with nitrous on a factory 400. Been running hard for several years at around 550-650 whp or so before cracking block in 2 in the lifter valley.

Its a wise investment to get a good block for your goals unless you can live with 500-600 whp which is like 10 psi

1992PonFirebird

I want to at least push 10 psi of boost even if I can't change it for strip and everything. I know that it costs to go fast and I'm a student so I can't afford to just blow all of my money but I do want something that is going to hold up and not just crap out on my right after I do the build. My brother is a mechanic and he is already going to take a look at the block when I'm done tearing it down. I had plans of changing the springs and push rods. I would love to get aluminum heads but they are no where close to being cheap. I am going to port my old heads. My carb isn't a blow through just yet because I haven't done the rebuild since the engine isn't ready. What block would you say is better? I know people have tons of money in their cars and that is great. This is my daily driver and I drag race on the weekends sometimes so I don't expect a super fast car I just want to make my car go faster. I can't afford to do everything at once so I want to do the engine first then start on other parts of the car. I will redo the engine when I'm older and have the money but I just want a fast car that will last me a few years. I love the look of the firebirds and I have one of the nicest in town but I am embarrassed to race anyone because my car is so slow and my dad has a 400 sbc in his 66 El Camino and it screams with just a stock rebuild. I want to rebuild my 400 and be able to go up to someone and race them and not have to worry about being left in the dust. Please any opinions would be great even if it isn't what I wanted to hear.

Orr89RocZ

iTrader: (20)

If a 1000 dollar set of heads is out of the budget then what are you going to do for trans and rear end and converter to hold the power? How you making the system and buying all the parts to make it a turbo motor? Being a daily driver reliability is even more important, and that can cost more money. All that little stuff adds up quick believe me. I have done 2 builds already on my 400 dart block. Never can fully estimate the cost of the project before hand because issues always pop up.

Do you have any porting experience at all? If none i would leave heads alone or have someone else work on them but imo its a waste of time and money. If you arent an experienced porter you risk making the heads worse than how they are now. Sending stock 400 heads off to port isnt very cost effective either.

A better bet would be something like new vortec heads from scogging dickey. I dont like flat tappet cams but your budget may dictate use of them. Stock fresh set of vortecs with upgraded springs will work good.

You say 10 psi is required but that means nothing. How much power you want to make? 10 psi on a vortec head motor vs 10 psi on a AFR or Dart 195-215 cc head is verry different in power. Pressure is measure of restriction. Larger heads cam flow more air and thus less restrictive so packing 10 psi air in that vs a small head and intake and small cam, theres a big difference in air mass being used.

What turbo do you have now? Will it even support a 400" motor?

I run a dart shp block. I feel its a great bang for the buck for 1000hp large inch motors. For under that much i'd feel safer using a 350 block based 383 instead of a 400 factory block.

Turbo cars suck. Its alot of work money and maintenance in my experience but once you put in the time and dollars they can be very rewarding

1gary

This is as good as it gets in terms of advise on turbo cars.Well said Orr.

1992PonFirebird

Yes I do have experience porting heads. The aluminum heads that I was looking at were close to $2000 and yes that is out of my price range. I expect problems to pop up and like I said before I know things aren't going to be cheap. The turbo set up I'm not worried about because I know some people that I could get piping from and I am a welder so I can't do that part easy. I have a Airesearch turbo. I don't know tons about turbos as I'm not very experienced in that or else I wouldn't be asking what all to do :/ Really my goal is to get to about 400 to 500 horsepower. My biggest worry was that I would crack a rod so that is why I want to do forged rods and I didn't know that about the hypereutectic so I will probably do forged pistons too. I haven't started tearing it apart so I don't know what type of crank is in it and I didn't know if I would be fine with a cast steel. My brother and I will rebuild the motor when I pull the 305 out and he said he knew somethings that he could get from his shop to "beef" it up some more.

1992PonFirebird

And for all the people saying that the 400 is a bad block to have it really isn't if you are willing to spend a little extra money. I know the 400s had a lot of cooling problems but there is some stuff you can do to help with cooling that's why most people split their block is because they don't do anything to help with the cooling

Orr89RocZ

iTrader: (20)

Cooling the block certainly helps but hp and torque will just as easily kill them. They really arent that strong. 350 blocks have been known to be stronger.

That turbo looks very small but hard to gauge size in the pic. Take some measurements of the compressor wheel and exhaust housing. Looks like some sort of flanged housing instead of the common vband round discharges and what kind of exhaust feed flange is it? t3 t4 or t6 square flanges? I got a feeling that turbo is gonna be to little. Integral wastegate also seems to indicate this is small but if you can tell us what it came out of if used, or measurements on the wheels and such, we can help you.

In all reality 400-500 hp can be done on the block with just heads cam and intake. No need for boost. Much better off this way for ease of install and reliability. Good heads dont need to be 2g's either. Set of 1300-1400 dollar afr 210's would support near 500 whp all motor if done right. Jegs brand castings are same as pro-filer and are good heads for less than 1100 but change the springs to match the cam you need.

N/a can likely use stock crank and hyper pistons.
Else if you really want turbo i wouldnt bother doing to much to the bottom end for 400-500 hp. Mild clean up on stock heads will be fine on top end. Just need some dish pistons to keep comp down for iron heads. Hypers can work but tune needs to be spot on. Forged pistons are abit more forgiving but still can melt down on bad tune. Hypers just tend to frag on detonation since they are harder and more brittle i believe.

Cast crank and decent rods will handle boosted power as long as you dont get to crazy with it and turn to many rpms.

1992PonFirebird

The turbo is a 53mm turbo. It isn't that small. Plus if it is a little small then it will spool faster. I know that I could get that much out of just the motor and I know that turbocharging an engine is more difficult but I love turbos and living in Colorado it is better to have a turbo because at higher altitudes the air is thinner and so with a turbo you can get that air. I talked to a few people and they said that I with a cast steel crank, forged rods, and hyper pistons with new springs, push rods, and ported heads and around 8 to 10 psi of boost just fine and I would probably be around 550 horsepower.

Orr89RocZ

iTrader: (20)

53 would work great if you had another to run a twin setup. Minimum id run on a single turbo 400 would be a T4 frame large exhaust housing 70mm on compressor. I run twin 70's on my 400 but i am also looking for double 500 hp. But they run ok on low boost and sub 600whp. A single 70 would work for 500whp. It would spool quiiiick! I spool my two by 3800 rpm but my motor has big heads and cam to breathe. Mild motor with one of them would light off by 2800 likely be very fun!

Ebay gt45 turbos are cheap and could work for a single. 400's have lots of airflow and small turbos will choke them. That 53mm may not get over 350 hp.

Borg warner s400 is a good turbo for you as well and fairly cheap but large t6 housing is better suited for higher rpm and higher power goals like 600-800 hp. Its big so harder to package.

1gary

The ref to a "cast" steel crank isn't correct.It's a cast crank that is stock in the 400's and nothing says high performance about it.Forged 5.7 rods and not the shorty 400 rods.I'm all in when you talk about the thinner air.Lucky the turbos are easier on engines than nitrous.

1992PonFirebird

They make cast iron and they make cast steel it isn't just "cast" and I know it isn't high performance? I think anyone could have told you that but it will work just fine with the way I am setting things up. Shorty 400 rods? What are you talking about? The 400 rods are 6" long. I have thought about doing a twin turbo but I just have no reason to since I don't want 1000+ hp. I was thinking about upgrading the turbo to a bigger one I just figured I would wait till I'm almost done with the build.

1gary

The OEM 400 rods are not 6".

For over forty yrs cast cranks are the ref and forged steel cranks are the ref's.

Sorry.I didn't tell you I was at the engine plant as a engine tester/dyno rm tech when the 400's where being built new.I do alot about them.Drag racing operation for about 40 yrs I guess.Seen alot and done alot.

Z28ricer

iTrader: (2)

That turbo will NOT work, not even close, you WILL need two of those, its not even close to the ballpark for being sized to run just one, efficiently.

whoaru99

You sure seem to be fighting hard against this request.

Orr89RocZ

iTrader: (20)

I thought stock 400 rods were 5.56" which are tiny. I would go atleast 5.7 to get abit better rod stroke ratio.

Also if you had two small twins they would work great. Just because its twins doesnt mean its 1000 hp. Twins help when goin after big hp but for smaller hp builds they can work great. Its very common for guys to go to junkyards and find small 4-6cyl car turbos and use them on mild v8's as twin turbos. I ran twin 60mm on my car and made around 800 hp. Still had room to grow but were great for lower hp as well.

A 53mm likely would be good for 700 hp in a twin setup and would spoool very fast in a 400.

If you upgrade to a better single turbo give the s400 borg warner a good look. Or master power magnum series in 72-76mm compressor, T4 .96 a/r preferably q-trim exhaust wheel but p-trim will work for lower rpm range with stock heads

1992PonFirebird

Yeah I love twin turbos a lot better. I have another baby turbo that is 42mm but it's junk. I have thought hard about either upgrading to a bigger turbo or doing the twin set up because I like twins because I could do a small turbo so it will spool faster. I know that just because I do twin turbos it will be 1000hp I was just saying because your set up with two 70mm turbos. Would you say keep the 53mm turbo and go with another one about the same size? Smaller? Bigger? Well maybe the rods are that small I don't know. But yeah I will upgrade them if they are that small I already had plans of that.
whoaru99- I am listening to people and I love all the help that they are giving me but I just want to make sure I get all things right. Orr89RocZ and 1Gary have been great help. And if I ever have any questions about turbos I know right where I would go.

Orr89RocZ

iTrader: (20)

Yeah what you have sounds like one of the stage 3 t3/t4 hybrid turbos. They all seem to be 50-56 mm depending and work great as twins for mild motors and lower hp goals.

I am planning on doing a single 70-72mm on my bolt on ls1 next summer. Just 500 whp. Should be capable 10 sec daily driver. Want to mimic my buddys old setup but he used a 74mm.

If i was able to go twins, id run t3/t4 hybrids in about low 50's mm

Ask this in the power adder board you will get more response from turbo guys there. Street lethal and project89 are well versed in the smaller turbos you can get on ebay for cheaap and would work for you

1992PonFirebird

Would you think that a twin 50mm turbos would be better than a single 70mm turbo set up? That would be a sweet set up! I looked at your tread about your build for your camaro and you did a great job!

Z28ricer

iTrader: (2)

Is that a 53mm exducer, or inducer on the turbo ? Its not too easy to judge its size by the pics you've posted, and there have been plenty of production turbos with exducers in that size range, need to know what it really is first to give you an idea of if it will work well, or be a complete waste of time.

Orr89RocZ

iTrader: (20)

Full specs on the turbo would be nice. Take covers off and measure both ends of each wheel. Get a good idea on size of the inlets and oulets of the housings as well.

Twins vs single just means abit more cost since you need 2 of everything but no real advantage or disadvantage performance wise imo

1992PonFirebird

If there is no real advantage then I might just buy my friend's 73mm turbo that he has and sell this one. I will try and take a look and measure everything but it might take me some time with work and school.

1gary

6" rods + rings spacers + turbo + street use = a bad idea.The 6" rod's pin location require ring spacers and for use on the street that with a turbo I think would be a bad idea,so avoid using 6" rods.When you order rods,tell them what it is for so if you need clearanced rods they will sell you the right ones.Same for the pistons so you end up buying the correct pistons for the turbo application/rod length, and considering which heads your using and if you end up having to deck the block for flatness.Most 400's deck has to be decked.The common question is if you want it to be decked at 0 deck for more compression or .010 down for less.All power adder engines has to have the top ring gaped differently as show in this chart:

1gary

Consider you engine as super charged for the top ring gap.You see where the piston to wall clearance for power adder engines is more as well on the chart.

No boring until you have the correct pistons in the hands of the machine shop so they can properly fit the bores to the pistons using deck plates and no decking until the machine shop has the piston/rod combo so they can mock it up for how much to take off the deck.If your game plan is to haft fill the block,of course do not bore the block until you have filled it and let that cure.

The first steps again is to sonic check the walls/check the bore size,mag the block for cracks. Then do the above knowing how lucky you are to have found a good core to work with.That is getting more rare these days.I've seen guys go through 4 cores before they found a good one.Got to remember these 400's are in the range of 30 to 40yrs old and god knows what the previous owners have done to them.That is why it is important to check every casting number and all the sizes.

Orr89RocZ

iTrader: (20)

I have 6" rods in my motor and seemed to be fine but i am also at 9.020" deck with higher compression height pistons so its still 0 decked. Still have ring support rails for oil ring. I have to tear down so not sure if my cylinder walls grooves i found were caused by rings or something falling into the bore like guide material... Need to investigate but its only on cyl 5 and 6 so thats odd.

6" should be ok for your goals. 5.7 would work fine too. Just gap rings right to account for high levels of heat but tune has alot of influence on that. I got alittle aggressive with mine

1gary

One of the rules I try to follow is to answer the questions asked by the O/P.Now I know you asked about a turbo 400.I do think there is no replacement for displacement.Thing is you do have added costs in using a 400 in extra steps to properly machine a 400 that will cost you money.I can promise you that a 383 would meet you goals as well.That the difference between a 400 and a 383 are marginal in output.So it comes down to if the machine costs of a 400 is close to the costs of a useable stroker kit/machine costs which one to pick??. There are a boat load of truck L31's 350's that run the yrs from 1996 to 2000.Aside from them being a stronger block,they has the huge advantage of being a hydro roller cam.They do come with Vortec heads that are a tad bit small for a 383,but for temporary use would be ok.Certainly better than the smog heads of a 400. And what is better than that at the same goals you outlined is the LSx engines turbo-ed.In fact the LSx exceed you goals when using a turbo.Those have been around for 14 yrs and to find them used cheaply is becoming more common place.

It is not that I have that much against 400's.We in our racing operation have used afew.It's that the other choices considering all the costs and what you end up with in the end are that much better especially when you consider the LSx options.

I am suggesting you think about this seriously so you end up with a no regrets build.

1gary

Orr my comment about 6" rods and ring spacers is the sealing ability is fine for race only applications,but when you add in street miles,it is much better to have the rings ride on the normal ring lands of a piston.

And no I refuse to get into a exchange with anyone about if 6" rods are better than 5.7 rods.LOL-ant gona happen with this kid.

Orr89RocZ

iTrader: (20)

I wasnt going there either lol

1992PonFirebird

Orr89RocZ- What is your compression ratio?

1gary

I think aside from your SCR,you need to consider the DCR more.Do need to know your SCR??. Yes. But your cam choice will impact that.

Orr89RocZ

iTrader: (20)

I am about 9 to 1 with aluminum. No issue with 93 oct gas and 15 psi and buttload of timing that i have seen.... Unless my cyl damage was from rings digging into bore wall from too much heat and pressure from too much timing and too lean. Lol

Took more timing than my old setup but its different head different cam, much bigger cam. Old setup has hit 18 psi at same compression with smaller cam and afr heads which typically sees less timing than others from what i have seen

1992PonFirebird

With the set up I want to do what compression would you suggest to run?

Orr89RocZ

iTrader: (20)

With iron heads no more than 9 to 1 but likely could get away with 9.5 if cam is right. Low boost. Should hold and make your power. Just dont crank up boost which is hard to do! Trust me. You will want more.

1gary

I would think you would set the SCR like that of a blower motor in the range of 8.5.Orr please chime in.

1992PonFirebird

Oh I know I will want more. But honestly with 8 to 10 psi of boost and close to 500 horsepower I will be just fine

Orr89RocZ

iTrader: (20)

Less would be safer with iron. But for low boost and being carb it will tolerate it. Carb with wet flow thru intake helps cool air charge more than efi.

If you have to buy new pistons shoot for lower than 9

1992PonFirebird

Yeah I will buy new pistons. I was thinking about hyper pistons but I don't know I just need to look into them more and see if they will hold up. Alright well I will probably shoot for around 8 to 1 compression ratio then. Thank you!

1gary

I just want to pursue more the topic of a higher SCR.Orr if you run a say 9.0 to 9.5 compression on a turbo with iron heads,in order to cool the intake charge does that force you to use a inter-cooler??. I would think that makes logical sense,but I don't know for sure.

With your twin turbo set up,are you using some sort of special oil filter set-up??. I have heard turbo's create carbon deposits that mean you have to change the oil more often and that is because the turbos themselves must have a clean oil source.Orr I don't know if that is a old wise tail or B.S. or what.Maybe you could shed some light on that.Are guys out there using a oil cooler with turbos to help that out some??.

Orr89RocZ

iTrader: (20)

I would always try to add an intercooler if you have the budget and room for one. It all helps in power and safety. But some setups dont need one to be effective. Carb setups tend to get away with abit more boost without intercooler because having fuel mix high up in the intake will cool air by the time it reaches the valve. This helps fight detonation.

Compression ratios and boost vary on applications. Head chamber can have influence on it as well as engine temps around chamber. Effective cooling systems can help in motors with higher compression. Spark plug heat ranges as well. All depends what you are after, but there are setups around 10 to 1 comp running few psi boost very well. But on something like that you are limited on boost before you reach the limit on your fuels octane level

Theoretically the more compression ratio you have the more power you can make. Works for turbos as well but you fight increased chamber temps and pressures to a point you stress the materials and run out of suitable octane fuels available to work. Its quite possible to run something like 11 to 1 on race gas with fancy intercooling and several pounds of boost. It would make big power but most guys seem to prefer running less compression and just adding more boost and improve cooling on the intake charge.

For mild street applications like 500 hp or few psi boost its not a bad idea to have abit more compression to help off boost driving experience. A motor with low comp breathing thru small piping and having restrictive turbo on exhaust side can be abit lazy compared to na motors of same compression. Once turbos are spinning its fine and if sized right you shouldnt have much problem with responsiveness in the motor. But abit more comp does help.
So for mild hp you basically build typical motor for pump gas and just throw a blower or turbo on it, intercool it and be happy.

I guess moral of story is run as much compression that will work for your hp goal on the fuel you will use. If it needs to be 500 hp, say 9.5 to 1 with 5-6 psi boost will do it on 93 oct. if you need 800 hp, you need more boost so compression needs to come down a touch. Try 8.5 to one and 14 psi or so.

If you had C16 race gas, or e85, you could make that 800 on same 9.5 to 1 comp and less boost than 14, likely 8-10 psi. Higher comp plus higher oct will allow you to tolerate more cyl pressure and heat via timing so more power is made on less boost

Orr89RocZ

iTrader: (20)

On the oil part i change my oil often and i use a turbo diesel oil. I change it more often than most would seem necessary, usually every couple hundred miles or after few passes down strip. The diesel oil seems to tolerate heat better and keeps oil pressure up at hot temps. Turbos being so hot can cook oil an its a good idea to add oil coolers. I have one but not installed yet. Need a place to mount it and i havent gotten there yet. With motor running rich and increased blowby from larger ring gaps and piston wall clearances, its also good to change oil to eliminate fuel in the oil.

Theres alot of heat in these systems so keeping oil clean and cool will help motor live imo

1992PonFirebird

I had plans of running an intercooler. So would you say use Turbo diesel oil? Should I do a do a oil cooler? And so you think I should run 6psi or would I be fine with running 8psi?

88FormulaF_Bomb

iTrader: (1)

i only read the original post.

imho, bowtie block or dont bother.


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1992PonFirebird

Well if you read the rest of the tread you would realize we already cover the block and the fact that I won't need a new one unless it's cracked

88FormulaF_Bomb

iTrader: (1)

im not saying you cant.im sure it will be fine,but why do you want to build a 600 horsepower racing small block and have something that important be a liability?


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1992PonFirebird

Because I'm not going to go ***** to the wall all the time and I'm not having that much horsepower if I was going more than what I want yes I would go with a different block

88FormulaF_Bomb

iTrader: (1)

then why turbo it? you can ruin that block with a good set of heads and a 11:1 compression without the added expense and hassle of going forced induction. there are easier ways to achieve 4-500 hp with 400 cubic inches. but i respect your decision to do what you do, and have fun doing it.


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1gary

[quote=88FormulaF_Bomb;5438559]then why turbo it? you can ruin that block with a good set of heads and a 11:1 compression without the added expense and hassle of going forced induction. there are easier ways to achieve 4-500 hp with 400 cubic inches. but i respect your decision to do what you do, and have fun doing it.

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