I recently came across an extremely well priced L98 long block motor. Now this will go in and replace the LG4 I had. So my questions are if I put on something like a Victor Junior or Performer RPM intake along with a holley 750 and out the rear run Edelbrock headers and a Hooker Cat-Back what kind of power will this make? The reason I ask is because I figure the motor will pick up more horsepower with the carb inherently wanting to rev higher than the stock TPI. Also will with the intake/exhaust I would most likely pick up an additional 60 to 70 horse right? Finally would porting the heads be a good idea while I am at it?
Thanks
Rob

 

You mentioned it reving higher with the carburator, as opposed to the TPI. So is it currently fuel injected? If so, I would leave like it is and go with a aftermarket intake, throttle body, etc. Also, it will depend on where the L98 came from, as far as the horsepower is concerned. Did it come from a Corvette for example? Also, was it rebuilt with stock parts, aftermarket parts, or not rebuilt at all? Need more info. before people can start giving you HP guesses....

 

The motor was a stock 87 camaro 350 TPI motor. It was a long block assembly so it does not come with an intake and tpi system on it. So to put the motor in my firebird i was going to run an aftermarket intake and carb.
Rob

 

OK, in my unprofessional opinion the motor stock was probably making around...230 HP? You're right, add the intake, carb, exhaust and I would say you could add around 60 HP. So you're up around 290 now. Port the heads, depending on the heads, and you could add another 15 HP. So now you're at 305 HP. (Again that is all just GUESSES). However if you get some after market heads, Edelbrock for example, along with a bigger cam, you could make some SERIOUS gains. Probably pushing 400 HP. IF the block is already out now, DEFINATELY put a bigger cam in, it will make a difference. (And it's only another $150, which isn't that much for an additional 20-30 HP). Just something to think about. Also, how many miles does it have on the motor? Was it recently rebuilt?

 

The motor is actually a brand new rebuild, so I am assuming a .030" bore out, maybe more but not much because this maker offers great warranties. Okay for the sake of discussion lets assume that for now I got with the stock heads but instead of running the stock cam I choose to run a XE268, I don't want to run more than that because for now I will be going with the stock converter. This with a Weiand Stealth Intake and a Holley 750 with the exhaust should put me in the 315-330 range correct? And now just to keep that mind of yours turning lets say I run Iron Eagle or Dart heads? Where would I be then?
Thanks a h*lluva lot with this!

 

Sorry, I meant to say Dart Iron Eagles or Vortecs.

 

I've got to admit I'm not real good with cams(at least figuring out max HP, etc.) but I'd say with that cam and those heads, you could be making close to 380 maybe even 400 HP. It should be a strong running motor. It'll be a 5.0 mustang for sure and keep if not whoop the 4 gen Z28's... That's my 2 cents.

 

Do you have a vacuum problem at idle with that cam? I have the same cam and I think I need a vacuum canister for my power brakes.

 

Honestly at this point I could not tell you, the motor is in the mail, if I do encounter and vacuum problems I will let you know when I get the motor in.

 

well I pulled the vacuum hose for the brakes off the master cylinder and plugged it. The car still died when I braked hard, all though it was very hard to brake hard with no power assist!
No I'm all most certain is is the carb.

 

OK I think you idea for the setup is great. I also would mil the heads to get more compression. i thin k the 350's had 9.0 If you mill you can get 10.0. This will really wake up your engine but it will need 92 octane at all times. Also your cam I think this would work. You will have stock internals so you shouldn't go past 6,000 so this cam will peak right around there and you performer rpm loses it around here also.
230/230 .480 lft @.5 w/108lsa
This is my opinion

 

I think that going carb is a good idea, however I would go either Holly intake and Holley carb or Edelbrock intake and edelbrock carb and not mix match em

 

if im not mistaken he said a weiand intake and a holley carb. i believe that holley owns weiand. and weiand doesnt make carburetors(that im aware of) so I believe his choice is very good

 

True Holley does own Weiand, but he said a Victor Jr or performer RPM intake with a Holley 750 carb. And if im not mistaken Edelbrock makes the performer rpm and Victor jr series, and I was only making the suggestion because I made that mistake once on a mustang, I put a performer intake and a holley 750 carb and they never quite ran perfect together I had to constantly re-adjust the carb until I threw a holley intake on there then it ran like a dream.

 

You can honestly run any carb/intake you want, and the difference in brands won't effect anything, as long as they bolt together, and are tuned right. If the bottom end is stock, it would be a bad idea to go with a victor jr intake, they are made for race motors butild to rev way past 6000. A 750cfm carb is too much for a 350 that won't be above 6000. A 650 will give you the same power, with a little more low end, and it will run better. Performer/Performer RPM intakes are both great IMO, I would recomend spending a little more for the RPM air gap one though. As far as the cam, don't get to wild, The stock cam and heads will give you good all around power with a good exhaust/intake. I'd say around 350hp, possibly more, but that's rough w/o desktop dyno handy anymore. That would be somewhere in the 5000-5500rpm range. The most imporntant thing is to get a well matched setup. You don't want your peak hp too much much over 5500. A slightly bigger than stock cam would be great, but don't overdo it. Also the stock heads would be fine for your app. aftermarket ones would push your peak hp too high, slowing you down, and possibly killing your engine if you let it rev much past 6000 for too long.

OR, you could go about the thing a diffrent way and get a holley stealth ram system, wich would give you the same type rpm ranges, but mabey a little more power, and some added benifits of FI.

Hope my suggestions help,
Nick

 

The stock heads will still be on the motor. The cam is going to be changed to a XE268 from comp cams. That way I will have a nice idle but the stock converter will still work for me. I never said I was running an edelbrock intake, so yes I will run a holley 750 and a Weiand Stealth intake. I am not running a 650 because this is just the current build-up. Future plans most likely include N20 or better internals and heads where I will need the better high end. As with most hot rodding I will probably never be completely satisfied so I am just building the motor right now to deal with current and potential future mods. The exhaust will be Hedman headers and y-pipe too, the edelbrock is just too much right now so.

 

Could someone Desktop Dyno this:
350 9.0/1 CR
Stock L98 Iron Heads
Comp Cams XE268
Weiand Stealth Low Profile Intake
Holley 750
Hedman Headers and Y-Pipe
Mallory Distributor
MSD Ignition
Hooker Cat-Back

Anything else I might be missing just assume is stock.