Jekyll & Hyde

First, this car is a daily driver so I need to keep some fuel mileage, and I am supposed to have emissions, but I can get away with a little bit. Second, I am doing this on a budget. Finally, I would like a powerband from ~1,500RPM - 6,000RPM. If you see anything that won't work or will be too much let me know. I will be doing most of my own tuning, with help of course, so include decent tuning. The valvetrain is my biggest concern.

The engine:
Stock 350 L98

The heads:
Aluminum L98 heads. These are going to be ported out to match the intake. Do these heads use standard valve stem lengths? I was going to purchase manley valves, 2.00/1.60.

The intake:
TPIS BigMouth manifold.
SuperRam, matched to runners. Runners matched to manifold.

The valvetrain:
Here is where I get lost. I want a noticeable idle, but since it is a daily, I need to keep fuel mileage and maintain stability. I was thinking of the 219/219 from LPE, but I have seen some faster with the XR cam from compcams. 220/230 @ .50 & .544/.544 with 1.5rr. I was going to run 1.6, but I can't find a spring kit that will handle it. It seems as if the 219 falls to quickly for the intake system. I know that the torque bands are both good for each other, but I won't mind losing a couple more ft/lbs. for a broader power band.

The gears:
I am trying to find a set of 3.45, but they are so freaking expensive. The only ones that I can find are 3.27 or 3.73. The 3.73 gears seems a little to big for street, I think that I will be spinning to much, and not utilizing the torque of this engine.

Rest:
Automatic Tranny, curb weight 3450, running std IROC rims, have suspension.

Thanks for all the help guys and gals.

BuckeyeROC

Looks like you did your homework. I can vouch for the LPE 219, my car ran 12.1 w/ it and no real tuning, just a PROM burnt with some guesses on it for the combo. Our brand new local F-body club is having a dyno day at the end of March, so it will FINALLY get tuned.

You might be better off with the 220/230 cam though with those heads, not sure how the intake/exhaust flow ratio will be. If you had AFR's or if the heads were going to flow similar (such as LPE ported L98's), I'd say the LPE 219.

As for springs, look around, I have the ones that came on the afr's w/ some 1.5 rr's, they are holding well so far. I'm not sure what the guys with higher lift are using, they'll need to chime in. I know AFR sells upgraded springs from the ones I have that'll handle more lift.

Definitely go for the 3.42/3.45 gears, seem to be perfect for a combo like this.

If you don't already have them, buy some sticky tires. Whether that be drag radials, et streets or slicks for you, you'll need at least the drag radials.

Jekyll & Hyde

Buck,

What tires are you using?

I have been watching your car since I started here. While doing the research I found who was running the SR and I found your site. Big Fan!!! Show me some numbers when you get it going.

The guy who is porting my heads has been able to get very close to Hutter Corvette's aluminum L98 port job. Here are the numbers if that helps.

OMINOUS_87

The L98 heads are gonna need some work, The intake port only flow ~200cfm max out of the box. 220-225 cfm should get you in the 12s pretty comfy, along with better numbers under max. The 219 cam should serve you well. Dont forget about running a decent exhaust.

OMINOUS_87

Flow Vs. the Vortecs, which everyone and their brother seems to be able to run 12s with pretty easily.

Jekyll & Hyde

I just don't like having to purchase another manifold. Just doesn't seem right since I already purchased the TPIS a long time ago.

BuckeyeROC

Thanks Maroon. I'm running the BFG Drag Radials on stock rims, 255/50/16. I don't drive the car too much, so I use them for my street tires too. They hook well when hot at the track, I can spin them pretty good on the street though.

OMINOUS_87

I am not recomending that you run out to buy the Vortecs, I am just trying to give you a flow benchmark so you know how far you need to take your head work to break deep into the 12s.

The L98 heads are going to need a great deal of work to be strong performers.

SweetS10v8

Havent heard any word of nitrous. Are you against it? People on here say they can get high 12s-low 13s on stock L98s just adding a hit of Nitrous. That wouldnt change your daily driving at all, but would make it faster only on occasion.

Buckeye, got a link to your club? I recently moved to OH. I am 1 1/2 hrs from Milan dragway and would come up to see other 3rd genners and hang out! I would love to get a dyno run in too while my car is stock. Maybe learn a little about prom tuning too!

edit: im a moron, i see the link in your sig..

formula350sd

iTrader: (2)

wel just my .02 on nitrous yeah its cheap and you nac go really fast with it but you cant always use the jug i feel a n/a motor is much better simply because you always have the power which is alot more fun if you ask me but hey what do i know

Jekyll & Hyde

The nitrous is after I get this all setup. I am concerned about the SuperRam and the nitrous. I have been reading on the vette forums that wet kits puddle up in the intake!!!

Jekyll & Hyde

I think the accel 219/219 cam will work best. I was looking at the E/I % of flow on the hutter vette and here they are against the AFR 180 (out of box).

Any percentage in the red is less than 77% between the exhaust and intake.

As you can see the flow is leaning towards the AFR heads, but not by much. In fact the L98 beats the AFR 180 on low end.

SweetS10v8

You would NEVER see me put Nitrous in any of my motors without adding fuel, puddling or not. Its just never gonna happen....

Jekyll & Hyde

Agreed!

Still, I am looking for 12's, on engine only. Maybe later I will put it on juice.

edit: typographical error, or was drinking too much and whatever it said made sense to me. - daniel

D Stroy H8

Everyone got all caught up on the heads - and noone suggested the 3.23s. You did say mileage was a concern, well the 3.23s are the way to go. Your combo has proven power. GO easy on the gears so you have less trouble hooking up, and significantly more mileage than 3.73. Also, they'll be better for highway speeds.

Jekyll & Hyde

Cool, thanks for the help. I am trying to find a local 9-bolt for cheap. Maybe then I can get some street slicks under the car.

Jekyll & Hyde

UPDATE:

Picked up a great set of L98 Aluminum heads for cheap. I am having trouble raising the money for the SuperRam, so I might put the cam and heads on, this way I can still have fun for a while, then switch the intake. It will be a little while, I am still trying to keep the cost at a minimum, but I will keep everyone informed.

Also, I will try to get some numbers from the dyno with the stock LTR, and then with the SR.

camarojoe

Hey did any of you guys buy chance purchase a set of heads on e-bay? My dad just sold some ported zz4 heads for about $500. I used to run these heads on my Iroc and it went low 13's with a SPRam, hot cam, and all kinds of problems. The vettes heads when ported for sure need to be used with a single pattern cam. I remember that setup with the hot cam had about a quarter-inch of carbon from all the overlap of that cam (reversion). Well, I might be exaggerating a little, but it was ridiculous.

Jekyll & Hyde

Nope, bought em local. I wish that I had known that, I probably would have bought those.

TheMysticWizard

iTrader: (1)

I take it that all these flow numbers are for Aluminum L98's? How do the Iron L98's stack up? I would love to go Aluminum L98's but I'm here in Cali, and I need heads with heat risers for SMOG

Just wondering.

I am planning an engine that is pretty close to what Maroon discribed, except I am going to be sticking to a stock intake, just ported out, maybe some aftermarket runners when I can afford them.

Jekyll & Hyde

You should be able to run the vortec heads in Cali. if you want to get some cheap iron heads. As for the stock, do a search for porting cast iron L98 heads, it is a four part series of on porting them out.

Are you sure that you can't run the L98 aluminum heads? They came on the vette, I think that you would only need to get the exhaust pass through hooked up. This is a tube that is directly connecting the headers/manifolds to the intake manifold. The cast iron heads have the pass through in the heads.

Firebreather

Are the vortec iron 885 the factory L98 heads for the Fbodys? They flow better than the Corvete aluminum ones??

Firebreather

Anyone has some flow #s on the factory iron heads from a 1991 L98? Are those the 083 heads?

mmcdjs

Hey. I am looking to build a 350 tpi for my daily driver, but I want to put in a good cam to allow me to mess with the rustangs that are running around. Assume that I am using the stock heads, what specific changes are recommended when building this engine...

which cam..

how much to bore over (.030 minimum)

etc...

thanks for the help!

TheMysticWizard

iTrader: (1)

As far as Vortec heads, I would need a new base plate, I looked at them on SDPC2000.com, they are expensive, and it says that the setup would not be legal in California. It seems like just since they EGR doesn't automatically make them legal, they have to be CARB approved for California.

Same goes for the Aluminum L98 Heads, no heat risers, and it seems the external piping for the EGR may be CARB approved, but how exactly would I go about running external EGR like that. It would require a different manifold correct?

I don't know, to me it seems easier to just stick with some ported out L98 Iron heads and loose a few cfm's, while still being completely safe and legal in they eyes of SMOG

Sometimes I hate California for all this smog crap, it makes it all too hard.

They should be 083 heads, as for flow numbers, that's what I was asking above... didn't get a clear answer.

Again, do Iron L98's flow the same as their Aluminum Brothers, the Aluminum L98 Corvette heads?

CraZ-28

This post is great. It's giving me some more ideas to go off of now. Only difference is that mine will be a 383 with HSR. Maroon keep on posting any info you get. Good luck brotha!

Kevin91Z

iTrader: (1)

Iron L98 heads suck, they are not worth the time. The flow is much worse than the aluminum L98 heads.

The Vortec and aluminum L98 heads can work in CA. I have the aluminum and my dad has the vortecs. Here is how I hooked up the EGR on my car:
http://para.noid.org/~thresher/image...1&dispsize=800

You have to scroll down to see the pics, the website is messed up. My dad's setup is similar, using the Scoggin Dickey Vortec TPI intake. Both of us passed CA smog with flying colors.

Do not put larger valves in the aluminum L98 heads. Its not worth the extra cost to gain only a couple CFM.

Also, every Dyno2000 test I have done with the LPE219 cam, it shows a loss of anywhere from 3 to 10 HP compared to other similar cams. I dont know why, but that's what it says.

My car is my daily driver, and it runs high 12's. You can click on the link in my sig to see all the parts I've hung on it.

Jekyll & Hyde

You can use the pipe from the exhaust to the port on the manifold. SDPC2000 has the kit for sale also.

083 heads DO NOT flow as well as their aluminum brother!! I will try to find some flow numbers, but once you port them out the aluminum will kill the cast iron 083 heads.


Pretty much what Kevin91Z had. His car is one that I got the idea for my setup off of. Look at his times with ported aluminum L98 heads.

Jekyll & Hyde

Ok, found em. Here are the stock cast iron numbers.

https://www.thirdgen.org/techbb2/sho...8+flow+numbers

14101083 heads 1.94 intake / 1.50 exhaust
numbers @ 28" of mercury for comparison

Intake
Lift_______CFM__Potential (based on 1.94 valve area)
0.097..........52.................66
0.194..........101...............131
0.291..........145...............196
0.388..........167...............226
0.485..........179...............242
0.582..........185...............253

Exhaust
Lift_______CFM___Potential (based on 1.50 valve area)
0.075..........35.................38
0.150..........62.................78
0.225..........87.................114
0.300..........105...............152
0.375..........106...............165
0.450..........106...............171

Jekyll & Hyde

Update:

I have recently decided that the auto will not hold up, so I have put the heads and cam on hold for a little bit.

I am going to swap to a t-5 with a rebuild kit from GForceTransmissions The rebuild kit has a .59 overdrive so I can use some firm gears and still have good fuel efficiency. I am thinking of using 3.70 gears and some nitto drag radials. Also, B&M ripper & centerforce clutch .

Will update when more happens.

As with anything else I ever post, please let me know if something won't work well with anything else. Such as gears are too high or something.

nmirocz

The T-5 has an overdrive? I thought only the T-56 had the overdrive 6th gear and the T-5 fifth gear was 1:1. I may be wrong of course.

Jekyll & Hyde

Yeah, T-5 has an overdrive. Most of the stock ones had a .73 overdrive. 4th was 1:1.

Jekyll & Hyde

As time goes by and so does money, plans have changed.

New Plan:
===========
Heads: Ported L98 heads matched to specs posted above.

Cam: XR269HR

Rockers: CC magnesiums 1.6 ratio

Intake: Waiting for BBK to show thiers. If I don't like it BBKs, I will use what I have in the garage...AS&M siamesed runners and matched plenum.

Rear: Can't find 3.45, going to use 3.27 till I do find some.

Tranny: Didn't like T5, stay with auto till it blows up. I am used to driving it and want to keep it a daily driver.

Tires: Nitto 555R for the street, don't think I will use slicks at the track.

===========

Average horsepower output at the engine for the setup above is around 410-420 and torque averages 450-460 ft/lbs. With some really good tuning, upper 12s should be reachable.

EDIT: All power averages are at the enigne and NOT at the wheels.