heads and cam recommendation

[redsoxsstink]

here is what I'm working with L98 TPI full exhaust. I am looking for some recommendations on a heads and cam setup and later on an intake. I am looking to be in the 400 rwhp without the intake and 450 rwhp with the intake. NO spray NO boost NO carb. this car must maintain Street manners and will be driven on the weekends through a 5spd and 3.73 gears.

I would like to keep all heads and cam components limited to COMP and RHS since I get great deals on them through my job. i understand the intake will be a different brand, but I want to get the heads and cam first.

things I need help with... im a bit lost with heads and cam specs and such. what would work the best for what I'm shooting for?

things that don't need to be included in thread... how long the 5speed will last and how quickly the 10bolt with explode, I know already they are weak.

[WildBillyT]

New engine.

Couple things:

1.) What does the bottom end look like? Pistons, rods, crank? Compression ratio?
2.) Stock CR is 9.5:1. You aren't going to run a 400whp cam with that, let alone have any semblance of street manners.
3.) Who is tuning this thing?

[redsoxsstink]

New engine.

What does the bottom end look like? Pistons, rods, crank? Compression ratio?
I'd like to keep compression to 10, bottom end will be freshened up when pulled

[The_Bishop]

In my opinion, you are asking a lot from a motor and induction system that put out a designed 225 horsepower. The biggest limiting factor if I'm remembering right, is the TPI intake.

Your next biggest problem is going to be tuning. You need to find someone who can tune the TPI motor, and that's going to need a chip burned. It's been a very long time, but somewhere in the back of my head I recall the computer needing to be modified (chip socket soldered in) to use burned chips but I might be mistaken about that.

With that power on tap, the five speed isn't going to live. They grenaded with alarming regularity at stock power levels on street tires when driven hard. Same thing with the rear axle.

Unless you are stone set on the TPI, you might be far better off with an LS based swap. The right 6.0 with a cam makes 400HP all day long.

[sweetbmxrider]

Lt swap if you want to bolt your trans to it, I'm assuming it will. Prob round $4-5k for the 400+ rwhp pending a few details. Ls swap, cam only and bolt ons will get you close pending trans.

[redsoxsstink]

tuning is not so much an issue I already have the auto prom and do the chip burning no biggie. if 450 hp is far fetched then I can work with something less. I don't really want to do ls since I can get gen II SBC parts so freaking cheap, I don't really want to disclose pricing, let's leave price/cost for engine components out.

the stock TPI intake going to be ditched at a later date for a TPIS unit or holley piece.

at this point I'm merely thinking out loud as far as options I do know I don't want to boost if anything NOS but I would really rather be N/A

[WildBillyT]

tuning is not so much an issue I already have the auto prom and do the chip burning no biggie. if 450 hp is far fetched then I can work with something less. I don't really want to do ls since I can get gen II SBC parts so freaking cheap.

the stock TPI intake going to be ditched at a later date for a TPIS unit or holley piece.

at this point I'm merely thinking out loud as far as options I do know I don't want to boost if anything NOS but I would really rather be N/A

You sir have a Gen I.

If you want, try going for 375-400 at the fly if you don't want to get too deep into it.

[sweetbmxrider]

lt1/4 is the gen 2.

You're going to spend a lot of money and be wayy behind in the power game. Lt1 will get there a little easier but there isn't much support for them anymore etc and people don't understand them for some reason. Ls is your best bet, a full bolt on ls1 in that thing with some minor weight reduction will be lots of fun and have lots of room to grow in the future with plenty of aftermarket support. And you will increase reliability and have pretty good fuel economy along with great street manners. The money you save now on your parts discounts will end up costing you in the long run.

[redsoxsstink]

my bad gen I

[Featherburner]

Build a 406.

[BonzoHansen]

is inspection important?

[WildBillyT]

is inspection important?

'86 so he can possibly QQ it.

[LTb1ow]

Mod motor in there.

[Paul Huryk]

I have some relevant experience and will give you my opinion.

450hp out of a 350 Gen 1 entails spinning the motor to a 6000rpm (or a bit more). I have a 400hp 350 at it peaks at 5500-5600 rpm.

There are two issues you have in terms of power:

1) Is the motor going to hold together at 450hp and 6000rpm+ (it probably will, but stuff happens)?

2) Will your choice of parts allow the motor to make both the power you want and be of high volumetric efficiency?

With an aftermarket TPI replacement manifold (vintage or new), 450ho is not a problem if the other parts are correctly matched.

But I've never heard of a stock TPI intake even cracking 350hp, let alone 400 or more. It comes down to the long runner design that boosts low RPM TQ at the expense of high rpm HP. No stock TPI motor makes its peak past 4500rpm, even the less intake limited 305.

In terms of parts, Comp Cams will make a cam to get you where you want, and RHS probably has a set of heads that will work too. But I would suggest just ditching the OEM TPI style and go right for a TPIS miniram - which is meant for high rpm hp. About $1,500 with the fuel rails and a new TB.

The last issue (and an important one) is the tuning of the computer for maximum power and streetability. TPI had an ancient computer with limited ability to change parameters, early ones (85 to 87 I believe) are way worse than the last few MAF ones. You can get a reprogrammed PROM, but it usually takes a few updates to get it optimal - it is not 1/100th as easy or comprehensive as late model OBDII cars to do.

[WildBillyT]

I have some relevant experience and will give you my opinion.

450hp out of a 350 Gen 1 entails spinning the motor to a 6000rpm (or a bit more). I have a 400hp 350 at it peaks at 5500-5600 rpm.

There are two issues you have in terms of power:

1) Is the motor going to hold together at 450hp and 6000rpm+ (it probably will, but stuff happens)?

2) Will your choice of parts allow the motor to make both the power you want and be of high volumetric efficiency?

With an aftermarket TPI replacement manifold (vintage or new), 450ho is not a problem if the other parts are correctly matched.

But I've never heard of a stock TPI intake even cracking 350hp, let alone 400 or more. It comes down to the long runner design that boosts low RPM TQ at the expense of high rpm HP. No stock TPI motor makes its peak past 4500rpm, even the less intake limited 305.

In terms of parts, Comp Cams will make a cam to get you where you want, and RHS probably has a set of heads that will work too. But I would suggest just ditching the OEM TPI style and go right for a TPIS miniram - which is meant for high rpm hp. About $1,500 with the fuel rails and a new TB.

The last issue (and an important one) is the tuning of the computer for maximum power and streetability. TPI had an ancient computer with limited ability to change parameters, early ones (85 to 87 I believe) are way worse than the last few MAF ones. You can get a reprogrammed PROM, but it usually takes a few updates to get it optimal - it is not 1/100th as easy or comprehensive as late model OBDII cars to do.

Paul,

Splitting hairs but he's talking about wheel horsepower. So probably closer to 500 at the fly, if that's the units you were using.

[Paul Huryk]

Paul,

Splitting hairs but he's talking about wheel horsepower. So probably closer to 500 at the fly, if that's the units you were using.

Guess I didn't notice that.

500hp is a 6500rpm peak - or a 383 at about 6000rpm. Never going to happen with a TPI intake, but doable with other alternatives.

[greenformula92]

Paul I have to agree with you. The TPI intake is designed for tq output. You will build a tq monster but be low on the HP side. The two biggest stepping stones are the heads and intake. That is where its limited the most. 400 fwhp is possible but you wwon't get 400 rwhp. And if you do somehow the t5 won't last through your dyno pull. I would seriously invest in a t56. Its basically a bolt in with the exception of a couple things. I would also punch it out and do a 355 or 383 and definitely go with a tpis mini ram or a stealth ram for your intake. I wouldn't go to radical on the can. Remember tpi is MPFI not SPFI meaning on a tpi the injectors fire left bank right bank. Not in the engine firing order. You may want to do some reasearch over TGO. There are a lot of guys making good power over on the board using tpi in one variation or another

[92REDBIRD]

My stock 305 tpi made close to 350 rwhp. With a stock T-5.
(With larger injectors and blower)

[Kat]

I've done 400 to the wheels thru a stalled auto and some archaic computer ...... Then again, I've dumped to much money into the damn engine. lol

[Paul Huryk]

My stock 305 tpi made close to 350 rwhp. With a stock T-5.
(With larger injectors and blower)

Putting a blower is an easy way to make power on a TPI car - easier to tune for some also.

Problem is that the TPI even with a supercharger is still going to exhibit the same power curve, although the TQ is going to be pumped way up (as is the HP).

Having seen quite a few 350s with Paxton and Vortechs barely making it to 350 fwhp in street trim, I'm curious what your car ran and what "stock" means...

[92REDBIRD]

Only slp runners, 58mm tb, larger injectors were on the 305. The motor was not touched.
T-5 only a clutch. Was not rebuilt.

[redsoxsstink]

Paul I have to agree with you. The TPI intake is designed for tq output. You will build a tq monster but be low on the HP side. The two biggest stepping stones are the heads and intake. That is where its limited the most. 400 fwhp is possible but you wwon't get 400 rwhp. And if you do somehow the t5 won't last through your dyno pull. I would seriously invest in a t56. Its basically a bolt in with the exception of a couple things. I would also punch it out and do a 355 or 383 and definitely go with a tpis mini ram or a stealth ram for your intake. I wouldn't go to radical on the can. Remember tpi is MPFI not SPFI meaning on a tpi the injectors fire left bank right bank. Not in the engine firing order. You may want to do some reasearch over TGO. There are a lot of guys making good power over on the board using tpi in one variation or another

i have done some research on TGO (86iroct5) and got ripped apart on my question. what everyone seems to be missing is the fact that i WILL do the intake, i dont need help with that. i KNOW the rear and trans will need to be bolstered. i need help with cam/head specs to get me near my goal, that is where im not so knowledgeable. which is what im not really getting help with.

i dont need people to tell me its impossible to make 1.25HP per cube on a 350.. im not a stickler for numbers, id be fine with 400 fwhp. i was kinda just thinking out loud with my original post if its not feasible thats ok im all ears to what is.

i dont want power adders period. i dont like them if anything it would be nitrous but i dont want that

/rant (not directed at anyone)

[redsoxsstink]

The last issue (and an important one) is the tuning of the computer for maximum power and streetability. TPI had an ancient computer with limited ability to change parameters, early ones (85 to 87 I believe) are way worse than the last few MAF ones. You can get a reprogrammed PROM, but it usually takes a few updates to get it optimal - it is not 1/100th as easy or comprehensive as late model OBDII cars to do.

i have a MAF car so that is a plus. i am lost with computers but have a good friend who burns chips and makes tunes and is pretty good at it (made a tune for his boosted MAP 305 TPI). im not really worried about the tune.

[wrong generation]

i have done some research on TGO (86iroct5) and got ripped apart on my question.

lol nick. thats not to suprising. tgo is a total waist of time and effort. when i use to have my thirdgens i got more help on a 2nd gen website then i could get on tgo.

[redsoxsstink]

lol nick. thats not to suprising. tgo is a total waist of time and effort. when i use to have my thirdgens i got more help on a 2nd gen website then i could get on tgo.

i go on there more for laugh, though the search function is pretty decent. most of the recent posts are BS

[Paul Huryk]

i have done some research on TGO (86iroct5) and got ripped apart on my question. what everyone seems to be missing is the fact that i WILL do the intake, i dont need help with that. i KNOW the rear and trans will need to be bolstered. i need help with cam/head specs to get me near my goal, that is where im not so knowledgeable. which is what im not really getting help with.

i dont need people to tell me its impossible to make 1.25HP per cube on a 350.. im not a stickler for numbers, id be fine with 400 fwhp. i was kinda just thinking out loud with my original post if its not feasible thats ok im all ears to what is.

i dont want power adders period. i dont like them if anything it would be nitrous but i dont want that

/rant (not directed at anyone)

400hp is not very hard with a 350 at all - even 450 or 500 is doable with the right parts. I have a 400hp 350 in my Camaro right now - mild cam, heads, and ancillary parts will get you there.

What I'm going to suggest you do is build your 400hp 350 with everything minus the high rpm intake (cam, heads, exhaust, fuel) and run it for a while with your stockish TPI style intake. Then when you are ready, change the intake and get all the HP you left on the table with the long tube runner design.

I'm not a fan of supercharging, but keep this in mind: a 550hp NA 350 is going to be barely streetable. But a 400hp 350 with a 150hp nitrous kit will work well on the street and the track with pretty darn good manners.

[redsoxsstink]

400hp is not very hard with a 350 at all - even 450 or 500 is doable with the right parts. I have a 400hp 350 in my Camaro right now - mild cam, heads, and ancillary parts will get you there.

What I'm going to suggest you do is build your 400hp 350 with everything minus the high rpm intake (cam, heads, exhaust, fuel) and run it for a while with your stockish TPI style intake. Then when you are ready, change the intake and get all the HP you left on the table with the long tube runner design.

I'm not a fan of supercharging, but keep this in mind: a 550hp NA 350 is going to be barely streetable. But a 400hp 350 with a 150hp nitrous kit will work well on the street and the track with pretty darn good manners.

that EXACTLY what i want to do. i dont know what spec products will get me in that range, the intake is simple and is the last thing i will do. the heads and cam are difficult as i dont know what im looking for.

[greenformula92]

that EXACTLY what i want to do. i dont know what spec products will get me in that range, the intake is simple and is the last thing i will do. the heads and cam are difficult as i dont know what im looking for.

I've heard guys having good success with something in the spec range of the LT4 hot cam. That may be a good option for you

[redsoxsstink]

comp recommended

part number 08-503-8
grind XR276HR
224/230 .503/.510 112*
http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=196&sb=2

with 180cc/64cc heads
http://www.racingheadservice.com/rhs/pro-actiontm-sbc-23-180cc-intake-runner-64cc-chamber-hydraulic-roller-assembled-cylinder-headhtml/

any opinions on this? this seems like a pretty decent recommendation from the research i have done

[sweetbmxrider]

What size are your combustion chambers stock? I don't think you'll be near your 450hp, or even 400, but I think it will be fun on the street so long as you have the heads milled so that the scr, dcr, and quench are in check. This is me assuming 64cc is wayyy too big.

[redsoxsstink]

What size are your combustion chambers stock? I don't think you'll be near your 450hp, or even 400, but I think it will be fun on the street so long as you have the heads milled so that the scr, dcr, and quench are in check. This is me assuming 64cc is wayyy too big.

64cc came factory on iron head L98

[sweetbmxrider]

Well you are going to want to get them milled down some to bump up the compression. How much? I have no idea, I barely know lt1s. Head gasket choice is going to matter as well to obtain proper quench. You'll need to know how far down the pistons sit. You should check out static compression ratio and dynamic compression ratio calculators. You'll have to find out what the l98's like though. Most lt1 guys run anywhere from 11.5-12.5:1 static pending the cam and 9:1 dynamic but we are a completely different monster with reverse cooling etc. I may be wrong in my assumptions here but I feel most will say get the compression up while maintaining proper quench. Guys will go anywhere from .035 to .050 but you have to be pretty careful with your measurements and rpm range with a tight quench.

And I don't think the parts are a bad choice, I think it should have good torque. I'm just not very familiar with your platform so take it lightly.

[Featherburner]

I'd go with these... http://www.racingheadservice.com/rhs/pro-actiontm-sbc-23-200cc-intake-runner-64cc-chamber-hydraulic-roller-assembled-cylinder-headhtml/

[Paul Huryk]

What size are your combustion chambers stock? I don't think you'll be near your 450hp, or even 400, but I think it will be fun on the street so long as you have the heads milled so that the scr, dcr, and quench are in check. This is me assuming 64cc is wayyy too big.

1 point of compression is worth 4% more power (if the gas will support it), about 15hp on a 400hp motor. So don't worry about that - as long as it is around 9:1, you will be fine. You can always add some timing. You can also use a thinner gasket.

[The_Bishop]

Need to be careful with the thinner gasket, as you really don't want to drop the clearance from the piston to the head under .035". Need to check if the piston is down in the hole or out of the hole.

[redsoxsstink]

stock comp is 9.3:1, L98 vettes run 10:1 with a smaller combustion chambers (58cc I believe). I may be able to get to 9.8:1 with the thinner gasket, past that I think there will be clearance issues.

[sweetbmxrider]

Its not just static though and you should really measure the piston height, never assume. You don't just want to slap a thinner gasket in there as quench matters. That is why I suggested milling the heads.

[greenformula92]

comp recommended

part number 08-503-8
grind XR276HR
224/230 .503/.510 112*
http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=196&sb=2

with 180cc/64cc heads
http://www.racingheadservice.com/rhs/pro-actiontm-sbc-23-180cc-intake-runner-64cc-chamber-hydraulic-roller-assembled-cylinder-headhtml/

any opinions on this? this seems like a pretty decent recommendation from the research i have done

That's a good combo. Also a popular one. After you do the manifold you might be able to get the power numbers you seek. You could back down the CC size to gain a little compression but I don't think it will matter much. I would do the 64cc and I think you will be very close to what you want. Until you switch to the short runner manifold the thing will be a tq monster for sure.

[Dudbird113]

Why the low compression?

[Kat]

I run 11.25:1 on 93 with 36d of total timing.. So far so go. Then again, I have pretty decently ported 56cc AFR 195's

[sweetbmxrider]

What kinda dyno numbers did you make? I know your car runs well at the track.

[Kat]

According to the dyno 4 years ago. 385hp/335tq. Then again I started the runs at 3800-6300 rpm and was out of injector. Since that I added the 42lb'ers and tuned the rest at the track.

[sweetbmxrider]

So safe to say your build is pretty inline with what the OP wants, correct?

[greenformula92]

Yeah I would say shooting for something along the lines of Kat's build will get you there. But we are talking 355. How much would a 350 make with the same mods? Well it will be close for sure but will be less. This has all been debated to the end of the world and back a million times for 28 years when tpi first came out.

[L695speed]

I know of a build with a TPI 350 where the guy is making 420+ but that is at the flywheel I believe. Even he admitted there really wasn't much more in it staying NA. At least in 350 form. Was using AFR 195s, and a TPIS Mini Ram intake. Sweet motor combination, but biggest flaw was tuning it with an OBDI computer. Best bet would be a megasquirt.

I looked into it, trying for 450-500 at the crank....decided with the money involved to do an about face on using the Gen one in a street car.

[Kat]

Uh I use the 730 ECM so yeah. Even with using the 385 on the dyno and 20 % loss through the drivetrain that makes it 485 or so crank hp.

This is why TGO can be misleading at times

Also I drive the vert everywhere. To dinner, track and back, drove it to floriduh and back. So why is using a gen I block wrong? ;)

Tho when I built my engine I just got done spending the cash on heads and intake when the bearings let go..... I would have done an LS instead haha

[L695speed]

Uh I use the 730 ECM so yeah. Even with using the 385 on the dyno and 20 % loss through the drivetrain that makes it 485 or so crank hp.

This is why TGO can be misleading at times

Also I drive the vert everywhere. To dinner, track and back, drove it to floriduh and back. So why is using a gen I block wrong? ;)

Tho when I built my engine I just got done spending the cash on heads and intake when the bearings let go..... I would have done an LS instead haha

Bad choice or words, I admit, nothing wrong with using a Gen one in a street car. Hell I'm doing so now. LOL. Just saying with 350 cubes and a TPI intake...not really much can do to get past 500 at the crank, let alone the wheels. I agree TGO can be misleading, I just was offered a deal on a LSX motor that I honestly would have been stupid to say no to. If the OP wants to play with a gen one, by all means do so. Nothing wrong with the choice, its the intake and cubes that can be limiting in his goal though.

[LTb1ow]

Bad choice or words, I admit, nothing wrong with using a Gen one in a street car. Hell I'm doing so now. LOL. Just saying with 350 cubes and a TPI intake...not really much can do to get past 500 at the crank, let alone the wheels. I agree TGO can be misleading, I just was offered a deal on a LSX motor that I honestly would have been stupid to say no to. If the OP wants to play with a gen one, by all means do so. Nothing wrong with the choice, its the intake and cubes that can be limiting in his goal though.

Granted Gen 1 is not entirely a Gen 2, but they are certainly not close to LSX stuff.

So, +500rwhp is not doable by either?

[sweetbmxrider]

Not when you top it off with tpi.

[L695speed]

Not when you top it off with tpi.

I agree with him here, stock TPI won't do it.

Easier with forced induction too...

[redsoxsstink]

well thanks for the advice everyone. i think im gonna put my pennies together and run with the setup COMP recommended, seems like it agrees with the masses. as long as im around the 400rwhp mark im happy, a little less is fine.

we will see where this takes me hopefully over the winter i can get everything in order and have a decent setup for the summer, maybe even OCMD :twisted:.

[Kat]

And for the cheap, a holley stealth ram is what I'm using.. Granted it is ported also.

I know of a guy on TGO that is selling a mini ram for like 800 dollars. Which is a great deal.. I've been thinking about grabbing that and see how my car reacts to it. Then again, its more money that I could be putting towards a blower for the GTO.. Hrmm

[redsoxsstink]

And for the cheap, a holley stealth ram is what I'm using.. Granted it is ported also.

I know of a guy on TGO that is selling a mini ram for like 800 dollars. Which is a great deal.. I've been thinking about grabbing that and see how my car reacts to it. Then again, its more money that I could be putting towards a blower for the GTO.. Hrmm

i can get a pretty good deal on a holley stealth ram which is what i plan i snatching eventually if there are no cheap mini rams around.

[greenformula92]

i can get a pretty good deal on a holley stealth ram which is what i plan i snatching eventually if there are no cheap mini rams around.

A HSR will work just fine for that comp setup. When you get it I would port match throughout to get the most out of it. Its a good manifold. You will retain some tq and gain some HP. The only draw back could be hood clearance. But I can't remember if that's only with the firebird or camaro. I know its one or the other.

[redsoxsstink]

A HSR will work just fine for that comp setup. When you get it I would port match throughout to get the most out of it. Its a good manifold. You will retain some tq and gain some HP. The only draw back could be hood clearance. But I can't remember if that's only with the firebird or camaro. I know its one or the other.

the camaro will clear fine, the firebirds had to trim a bit of the hood bracing.

[greenformula92]

the camaro will clear fine, the firebirds had to trim a bit of the hood bracing.

I knew it was one of them. Nothing a cowl or ram air hood can't fix :)