400 HP L98
 

I have a spare car which is a third gen (1990) with the L98 tpi motor I think and it is an auto. I was wondering if it is possible to reach 400 hp at the crank in under $2500? There are tons of threads asking the exact same questions but many are old and seem to suggest ZZ9 which is something I cannot find, maybe it was available back in 2005. I found AFR 195 heads ($1700) which I think can take the car to 300 hp. Can anyone suggest which cams or where to look? If 400 Hp is not possible then how far can I get within $2500 or how much do I need to spend for 400Hp?

Re: 400 HP L98
 

To reach that level of power for that amount of money you’re probably looking at full exhaust for sure. Perhaps the most cost effective top end would be a HSR and some decent heads. Lots of cams out there that are reasonable. 400 at the crank will require tuning and other driveline upgrades as well. Of course the first order of business would be a full tune up and making sure brakes and suspension can support that power as well

Re: 400 HP L98
 

I am still searching and came across 280XFI cams. Are these worth it? If not can you give me an idea of what cam to search for? I have an auto so which cam can I get that can help me reach my goal and avoid a stall converter? I am ignorant when it comes to these modifications and can't seem to piece together a recipe for my goal. If I am saying something wrong it is probably because of what I have read on the internet and misunderstood.

When you say some decent heads would AFR heads be any good? The HSR42 claims to give about 58-75 extra hp with an air filter and some mufflers, is this true? (https://www.mikuni.com/fs-products_guides.html).

Brakes have been replaced and other service I have done myself, the car runs fines and drives safely. As far as tuning goes I will have to look up someone who can tune the car near me but the tune can only come after the right modifications.

Re: 400 HP L98
 

The ZZ9 cam was an old Tuned Port Injection Specialties (TPIS) cam. It's still available, but it's not the route I'd go. https://tpis.com/collections/cams I think the more modern XFI cams are better.

Hear me out though. First of all $2500 isn't very much. Second, full headers/exhaust on the engine, better rear end gears and SMALL stall converter can be done for less that $2500, and will give you more bang for your buck than 400hp through a stock gear and stall set-up, AND have totally reliable driving manners. You'd HAVE to do exhaust either way. I put a 3.27 gear and a 2200 stall in my L98 way back when....it was probably pushing 260 or 270 crank HP, and the gear and stall made it an entirely different car! ....you could probably BUY the heads and the cam, gaskets, fluids, hardware, valvetrain for $2500...maybe...MAYBE.....but that's not a given. Then there's exhaust, which is a must....then intake....which is a must....then of course tuning, and that's assuming that power doesn't find the rest of the weak links, which is WILL....old trans is sure to blow....Ugh...been there done that. Do the engine last. I'm telling ya. The power is wasted through the rest of the "stock" car, and the updgraded rear/stall/exhaust will provide more "fun" even with a stock engine.

What do you wanna DO with the car?

Re: 400 HP L98
 

I'm a fan of not modding the SBC thats in there. However, if you don't want to do a swap to an LS engine, here's what I would do with your $2500 if you want to spend it on the engine alone.

Option 1:
$1000 - First Intake (complete aftermarket TPI Intake)
$800 - good shorty headers w/y-pipe
$600 - Full 3" cat-back..
That puts you around $2400. But you will still have other expenses. You still won't make 400hp. But you will make a good deal more power than stock. This would get you close to 300hp, and 400tq, if not over 400tq.

Option 2:
$750 - HSR intake
$800 - good shorty headers w/y-pipe
$600 Full 3" exhaust.
You have a bit more here, I would save the rest and save for a a heads/cam combo that can take advantage of the HSR.

The problem with going to something like AFR heads is the sheer cost of them, and the fact that now all of your budget is blown on heads, and you now don't have enough money left over to pay for parts that won't choke the heads. AFR195s are big boy heads, and they need big-boy intake, exhaust, and cam parts to work at their best.

Example is my engine in my GTA. I have the AFR195 heads. To actually use the flow potential of these heads on a 350, I need to spin the car over 6000rpm. In fact, on my last data logging run this morning I nearly crossed the 7000rpm threshold. The data log reported 6,923rpm and the car is making in the range of 450-500hp at the crank.

Re: 400 HP L98
 

That HSR product you listed is a motorcylce carb. When WE say HSR, we mean a Holley Stealth Ram. The brand Holley also owns Weind, and they sell the same intake under their name, but we just call 'em all HSR's! You can buy just the intake manifold itself, or the whole fuel injections set up, with wirings, sensors, injectors etc. etc. You don't need that as you 'll just reuse the electronics and everything for your TPI intake. You just buy and install the new HSR intake. Might have to buy fuel rails too, as I've never bought one of these myself, but either way, it's a great, inexpensive system.

Still....by itself, that HSR isn't gonna make a huge difference. The engine is a system. The heads, cam and intake need to work together. middle of the road parts, when properly chosen as part of the whole system will perform better than a poorly selected hodge podge of great parts. ...and then that engine, is part of the whole driveline, which again operates as a system. If the transmission and rear end aren't properly geared/stalled for the given engine, again....it won't perform well.

Re: 400 HP L98
 

400 HP isn't going to happen for $2500. Just get that idea out of your head. You will make mistakes in the process due to a lack of experience - that factor alone will wreck the budget.

FIRST intake.

Vortec heads.

Cam.

Full exhaust.

Tuning.

The absolute First, most important question you need to answer is: How will you tune it? What is your plan? Who will tune it and on what dyno? What management systems will they/wont they tune? Remember - you can't make ANY SIGNIFICANT changes to computer controlled fuel injection without reprogramming the computer. What's you game plan for the computer?

GD

Re: 400 HP L98
 

I echo this.

The biggest problem when you talk about TPI and horsepower is the RPM limitations in the stock intake. You have to address this if you really want to get the engine to HP well and give up some lower end torque. Then you have to be able to tune such a change. This means and aftermarket ECM or investing in the equipment to burn your own prom. You will absolutely have to un-choke the manifolds. The factory L98 pieces are crap. Long tubes or nothing here IMO. The factory fuel system was't designed with 400hp in mind. You will need injectors and a pump to support this.

So, you are a fuel pump, injectors, headers, intake manifold, and tuning away from being able to support 400hp. Your budget just doesn't support getting to 400hp, even at the crank, as you are starting with an engine that made around 225hp at the crank from the factory.

To get to 400, you basically have to address everything... heads, cam, intake, headers, fuel injectors, pump, and ECM.

If you just want to be faster, how about long tube headers, 3.42 gear, 2400RPM stall converter, 1.6RR and a small Nitrous kit.

Biggest thing is to always check the overall health before starting any mod path.

Re: 400 HP L98
 

TPI itself is the challenge... 400HP will need to happen at higher RPM, something Factory style TPI runners do not work well with.

Re: 400 HP L98
 

If you want 400 HP then nitrous or LS is your route

Re: 400 HP L98
 

LS... you won't regret it.

Re: 400 HP L98
 

As said above, LS would be the easy path to 400HP.

$2500 is a long way from getting a full swap done.

I'd go with Abucaba's recommendation. Setup the car to go faster and it will be faster.

Re: 400 HP L98
 

No; you'll spend almost that amount in just rebuilding/upgrading the rotating assembly (crank/rods/pistons/machine work). The TPI will have to go in favor of something modern, user-friendly and that doesn't quit at 4500RPM.

Adding a cam and cylinder heads to an otherwise stock, 30-year-old short block is also a bad idea; the minimal power increase just isn't worth the trouble and expense, and old, worn rings and bearings won't hold up.


How about the rest of the powertrain? The old trans will require an upgrade, as will the rear end. With such a limited budget, you'd do well to simply drive the car as-is, and start saving your $$$ for a future LS/transmission/rear-end swap. As far as how much all that will cost, that's dependent on where you live, the resources (salvage yards) available to you, and your experience level relative to whether you'll be doing all the work or you have to pay someone else (think, big $$$) to do the swap. This isn't an inexpensive hobby; look before you leap.


However you decide to proceed, GL.

Re: 400 HP L98
 

You are making a lot of assumptions. My "30-year-old short block" is as healthy as can be and is getting hit with boost and no blow by. He didn't include much about mileage or condition. I would toss a Cam in mine, with no concerns. My car only has 60K miles though and passes a compression test in ideal conditions. I would have to pull my notes out to get the right numbers but it was less than 5% between all cylinders.

Re: 400 HP L98
 

I wouldn't say it's impossible. I was able to get to 365hp (300rwhp) from a stock 305 LG4 for ~$2,000. If I had a 350 to start with it would have likely made 400hp. This was with a turbo, blowthrough carb, and a lot of custom diy fab work. It just depends on your goals.

Re: 400 HP L98
 

Lol. OP seems to have disappeared.

Re: 400 HP L98
 

Not really surprising, considering that most new posters arrive here already having been misguided in their assumptions of what is relatively easily/cheaply possible to attain due to what gets posted on other, far-less technically-accurate social media websites. These days, horsepower numbers are thrown around like a feather in the wind. Detroit is also a major player in those HP games, and their published numbers are highly influential. Noobs often fail to realize that their stock third-gen engines are nothing like what is being built today, even when they were new.

When reality bites, it can be a rude wake-up.

ETA:
This post isn't necessarily aimed at you, OP; it's just an observation based on what I see all over the interwebz. And again, whatever you decide to do---or not do---GL.