I am trying to get at least 300 RWHP with an L98 engine. I have had a few suggestions just trying to see what others did to increase the HP for this marvelous engine.

 

Intakes, headers, exhaust and dyno tuning. What are we talking about money wise?

 

You'll need a miniram style intake, cam, headers, exhaust, and possibly heads if you don't have the '113 heads. That should get you to 300 rwhp or more.

 

Even if he had 113 heads they are not the greatest at this point and should be refreshed and while you are there, might as well fluff them up a bit.

I know I installed an LPE 383 and before I left, John L asked me if the trans was stock. I asked why and he said that it would die within a year. Made it 9 months grannying the thing.

 

I haven't touched the longblock, 128 heads and am still using the stock flat tap cam and exhaust manifolds on my 86. My ET says I'm running 315 rwhp bout but I'd wager the dyno would show lower since I focus on efficiency. These engines/car will run decent if you put in some work. Intake, cam and exhaust should get you around 300, the alum heads 128/113 came on some of the early zz engines, so they ain't no boat anchors and comparable to some camelbacks. Still modern good brand heads are the easiest HP and good $ spent.

 

To get more than a little over stock with the cam, I would think you'd need some tuning too?

 

Not to be the bearer of bad news... but that seems like a STRETCH to me. 315 rwhp on stock cam, stock manifolds, and stock heads... That would be like a 100 hp gain over completely stock...

 

Aklim-I have a mild tune I got online, I don't think it's ideal and am planning to do some tuning myself just not decided on how to go about it yet.

dan-I find it harder to believe you haven't done better with some of the parts you have. I know many ways to make cars fast and continue to learn. A stock engine/car is bleeding power left and right, you just gotta know how to plug the holes. I'm not even done working this car and my goal is to make it as fast as I can w/o changing the cam or heads, then maybe I'll port them and use a cam that many would consider small. If your in this hobby long enough you'll understand, if you don't quit.

 

^You're obviously good at improving drivetrain efficiency, resulting in "good" ET's (what ever they are) but...
ET's are not a good or reliable metric from which to calc HP. Why? Set up and driving. A 400 hp 'Vette can trap anywhere from high 11's to low 13's....but it'll trap pretty consistently around 114 or so. TRAP is the metric from which to calculate HP. Not ET.

I agree w/Daniel....I doubt 315 RWHP.

 

 

I guarantee, unless you are extremely lucky, it isn't ideal. IF it is, you just won the lottery. Online mild tune means extremely conservative. If I were tuning without at least datalogs, do you think I would put an aggressive tune or something that is a "CYA Tune"? Only way I know of is to dyno tune or at the very least, take readings and tune and retune and retune till perfect.

315 RWHP is how much after drivetrain loss? So how much do you think I make since I have 420 RWHP on the dyno? Conservatively, I kinda think just south of 500, maybe 480 since I have a 700R4. So if you have 315 RWHP, you are probably making north of 350 at the crank. The stock engine is rated at 240 at the crank so you'd have to be able to staunch the loss by 110 HP which is pretty good. 20 years ago, even with the Superram intake and Tri-Y headers and exhaust, I had it tuned at LPE and I forgot the exact numbers but there was no way I could make 100HP. So exactly what was done with a mild tune and what else did you have to change to make this 110 HP?

 

Thanks guys, really good information on this site. I think I am going with the heads headers and cam set-up. I did communicate with another guy here earlier and he suggested a 3000 stall, would that be something worth looking into?

 

Ask Precision Industries. They make a TC for our car. Sounds a little higher than I would like

 

If you don't change that intake manifold then you probably won't get to 300 rwhp.

 

And a more aggressive tune instead of some canned version. SOTP dyno is incredibly susceptive to fantasies and good thoughts. SOTP dyno said the car was running smoothly, injector bench said they weren't all at the same rate and one was partially clogged. SOTP dyno didn't register changes when the injectors came back. On my other cars, SOTP didn't register change after cleaning and testing of injectors but mpg did.

 

Yeah I left that off the list however, I do plan on the FAST intake I just wish it did not cost 900 bucks for just the intake.

 

I agree on the tune deal and I am not that lucky!

I've done basic stuff like 1.6 rockers, cats delete with hi-flow muffler and good exhaust, UD pulleys, delete all the crap that you don't really need that robs a little here n there. I've spent a lot of time porting the intake plenum, shortened the slp runners to about 15.5" and I want to try another inch(basically a DYI superram when you do that, shorter runners and more plenum volume)(LS3/FAST LS intakes are about 14"). The base wasn't over ported and hogged out like many who only care about cfm. LOL I always get a kick out of how people compare the base to the performer intake flow numbers when a carb intake has to flow fuel as well. Same with header size people way too often go too big and when you just make everything match and flow similar it works really well. Rock solid ignition! Too many small things tah list. I try and control heat under hood as well as intake temp. I can go for a drive and the plenum will be cool to the touch and never gets over lukewarm with the 5 mods I do to help keep it cool. I like to have people touch my valve cover then the plenum to see the huge difference. Corvettes in general heat is a big power robber!

Anyways lots of work and time spent on all the little tricks I've learned. Much of the info is on this forum or others, just gotta look for it.

 

I would never recommend someone go with a 3000 stall TC if they plan to drive it alot on the street. You will not like it.

 

Thanks for the advice.

 

A lot of the little things do net a little here and there but getting it up to spec is probably going to give you the "sunny day" performance numbers, which is what GM rates the engine at. IIRC, that is about 240HP. All those little tricks, I'd be surprised if they give you 20HP. So at 260, including drivetrain losses, I really don't know how you came up with 315 RWHP.

How much do you think you are making at the crank if we put the engine on an engine dyno? You really think the little tricks are going to net 100HP? Call me a skeptic but I don't see how. With the throttle body running empty vs the stock cleaner that is cut out with a K&N (SD not MAF), I was probably making 4 HP difference. 2 with just a filter element stuck on the TB.