19doug90

pretty easy question. I know the tpi motor falls on its face at 4500 rpms cause of the intake.

But once my intake is replaced, since im throwing a cam in how high rpm can stock l98 heads support, and how much higher rpm do you think you would get out of minor portingto the heads (dont know what was done by previous owner exactly, havent had the motor apart yet)

sofakingdom

iTrader: (1)

At "pump gas" compression levels, they'll support somthing in the 400-425 HP range, with light home porting.

Of course, that's with TOTALLY OPTIMIZED everything around them; large tube headers, single-plane intake, big carb, etc.

Probably 375 is reasonable for the home port job to attain in street trim.

19doug90

thats very good to know, i was probably a little more curious to what rpm range they are capable of peak hp.

The motor will have a hsr intake manifold, the port on the heads was done 2 owners ago by a shop not just a home port. So im more wondering how big of a duration i can go with a cam on my 350? Want to make sure im matching the powerband as best as possible.

sofakingdom

iTrader: (1)

A 350 with that combo will probably do its peak HP in the 5800-600 sort of neighborhood; so I'd suggest a cam that peaks somewhere about there in a 350. Which will be a 224/230, 227/235, something about like that; with peak lifts in the .510" - 520" range. Keep the lobe centers close for best torque (110 degrees, certainly no more than 112), since you'll be doing plenty of chip tuning anyway, it won't matter so much that a stock tune won't run right.

klumb15

iTrader: (1)

i'm running an almost identical setup...224/230 duration, .503/.510 lift, l98 aluminum heads (mild porting), HSR...from the people i've talked to it should lay down like 300-325 on the dyno, approx 375-400 at the crank...

19doug90

sweet what lsa are you running, which cam exactly is it? any idea on tq numbers? and is the motor put together yet? im looking at about 3-4 months before my girl is ont he road.

klumb15

iTrader: (1)

its the comp cams XR276HR, not sure what the LSA, pretty sure its a 110...i'll double check tho....the motor is together and running, needs some hardcore tuning tho...i've been talking with a dyno shop, and i'm hoping to get it there early spring, like around march or so...

i'm guessing torque is a bit shy of 400...but who knows...its way out of whack, and the thing still rips...

klumb15

iTrader: (1)

nope sorry its on a 112...

19doug90

thats awesome gives me a ton of hope

ah i see in your sig it says you have vet motor? does that mean you have the smaller cc aluminum heads? i hope not lol, my iron aluminum heads are going to kill my hopes of any power.

klumb15

iTrader: (1)

lol, yup they are 58cc aluminums...sorry man...but the iron's can support some hp too...mine are stock port sizes i believe, but we had a buddy of mine do the valve job and spring work, so he could make my bigger springs and single groove valves work...so i have a lot of machining into the valvetrain, but i'm not too sure about the porting. They look to be ported mildly, just because the metal looked tampered with. But not positively sure. But do some investigating on porting, and go to town on your heads. Why pay somebody to do something you can do. Its fairly simple, and eaiser with iron heads, well kinda. they have a lesser margin of error, but its a harder metal to remove...plus, they are dime a dozen, if ya screw it up, pick up another pair for next to nothin..

but with my cam, and your heads, you should be able to pull a modest 350 out of it. I have 1.6rr also, making the lift conseribly more, (.533/5.43) around...thats why i needed the spring and valve work..

19doug90

lol im getting less optimistic by the second.

Are my iron's 64cc or 72? i forget, 64 isnt too bad shouldnt kill too much of my hp.

I know the stock heads cant really go above .50 lift forget why, forgive my ignorance im only 19 and just getting into cars in the last 2 years, not as up to speed as id like to be in some ways.

I'll take it to a good shop and see what they can do about my valve train. See if i can get enough lift out of it to make descent power.

My goal was 300 hp, 350 lb ft to the wheels with a computer tune. I would be extatic if i saw those numbers

camarodarrell

Go to LT1intake.com, there's a car on there with LT1 intake, stock gasket matched iron L98 heads, and the same 224/230 cam, it made 300 hp to the rear wheels. Not bad for non ported stock iron heads. Oh yeah, the L98 iron heads are 64 cc combustion chambers.

klumb15

iTrader: (1)

yup they are 64cc, you could always get them shaved...you should most definately reach your goal tho...

i'm 19 also, your in the same boat i was, i just started my project a bit earlier...

but you should be able to achieve what you want, and if you need to get machining done, it really won't cost too much. I had my spring pockets bored and deepened, and i had single groove valves installed, instead of the stock 3 groove ones, the single groove allows the spring to install higher, making more spring travel. but good luck with everything, and there are tons of members here to guide you through the journey..they certainly helped me when i went through it...

xpndbl3

iTrader: (5)

are you from markham IL by chance? if so there's tons of us around here who you could ask for help from.

19doug90

wish i was, thanks for the offer.

Not the first time ive been asked that, need to change my info to read ontario canada

19doug90

rehashing this thread i just thought of something.

Klumb what sized TB are you using with your combo?

I'm wondering if my stock 48mm can keep up with this combo, or if im holding back power by not going to a 52mm?

klumb15

iTrader: (1)

i'd go to a 52mm just to be safe...all tho a 48mm might be alright..

I'm running a twin 58mm TPIS unit, just because its a 500 dollar part i got for 325 or so, and it looks pretty mean so I bought it ...i know its overkill tho...

19doug90

wow do you live on this board? lol i got a reply in 10 minutes! thats just funny.

Ya hopefully i can find someone selling a TB for cheap when it comes down to it. Theyre freaking expensive, but ill step up to a 52 if i can.

klumb15

iTrader: (1)

yea i do.. ..i'm a college student, and i do my homework right in front of my computer, so right when i get an email i respond to it...
lol

but yea keep your eye out on the parts for sale section, maybe even post a wanted ad in the parts wanted section, your bound to come up with a BBK for cheap somewhere...

Rob Wade

Doug I would stay with the 48 mm TB to start. It is easily capable of the HP levels your hoping for. It will also give you a little better throttle response than the 52mm. I am currenty building my L98 and I have both a 48 and a 52. I am going to fire the new motor on the 48 and tune it and then if I'm not happy I'll go to the 52, but only because I have it. I would save that money to use elseware.

Dyno Don

iTrader: (7)

If those heads were that good....no one would be replacing them

19doug90

wow way to go back all the way to the beginning of the thread. And actually those numbers are pretty close. I'm fairly certain with some valvetrain work, a big cam, hsr, mildly ported heads, and full exhaust, and custom tune that i can put down 300 to the wheels, which is around 345 to the engine, hes going a little overkill on the numbers but not by a ton.

19doug90

Thats what i was thinking, i seriously doubt my 48mm is going to not be able to support as much airflow as my heads can handle. On the other hand my buddy just bought a bbk used off some guy and it does look awful sexy if i can find one for cheap used ill get it, otherwise ill probably stick with the stocker.

Figured i would ask just encase i got a, whooa if you dont put a 52 on youre killing your hp. Didnt think i would tho.

rideon1200

I see the phrase "home porting" what does this mean?

19doug90

means you pulled the heads off your car, and took a die grinder to em. As opposed to taking them to a speed shop and having them done by a professional who has lots of mesuring tools and a flow bench and such.

For minor porting work, a home port can definitly free up some hp, and your only cost is time and tools

rideon1200

When home porting is there anyway you can screw up or is freeing up space good no matter what. Are we just talking about smoothing out ports?

Rob Wade

You do need to have some undersatnding of what it is you need to accomplish. Do a search, there is lots of info here. Yes you can screw up, but usually thats just from being ignorant and not knowing what it is you need to do. Do your homework first, and then see if its something you can handle.