Between todays LS engines and yesteryear, its the head design and the sophistication of modern fuel injection systems

 

Well what is the cost. If say $900 that comes to $30/chp, not too shabby me thinks.

The late L98 made about 240chp, with some simple bolt-ons and mods it can be coaxed to around 300chp and still have the well know low end torque.

Do heads, cam, FL headers and intake mods and you have pushed it into the high 300chp range with 400chp possible, while retaining most of that low end torque.

Perhaps at their "potential", considering the requirements "package". More efficient emission control systems, better computers and sensors, and a number of other tech advances have lead to improvements over the years.

 

I know my L98 with just a Miniram dynos right where most healthy stock LT1s are and peak at about the same rpms. I do have base timing set at 12 degrees though.

 

Is something easier being missed on upgrading an L98? The manifolds seem impressive. The heads -- especially on a 89 were improved. A 350, V8 is still a 350 V8. Why does everyone say Chevy screwed us?
Greg, The L98 is an excellent engine. Wasn't this still in the time frame when we had just gone thur the insurance wars, fuel crisis and decline of the muscle cars? General Motors ia always slow to react.
In 67, a base motor had 300 hourse, a fuelie had 375.
The ways of measuring HP changed in the 70"s because of the insurance companies and they took a long while to come back.
From a marketing standpoint, GM couldn't design/release a brand new motor design and have it equal to the L98.
As said above " an engine is just an air pump", it's all about effiency.
The bottom line for this "air pump" is that you can get 500+ hp from a 327, a 350, a L98, a LT1, etc.
We have a Vintage Winston Cup car with a 358 Chev. running a carb that puts out 600 to 730 hp depending on which heads we run. One look inside of the heads at the ports and the size of the valves and you can start to see where this HP is coming from.

 

Gregg, the 1989 L98 is a really good engine. Why try to make it an LT1?
A good exhaust system, 1.6 roller rockers, and the free mods, and you're at LT1 power levels with L98 torque.

 

Well, but nobody likes how small the runners are on the L98. If you got large tube runners, better base and even a bigger plenum, you could probably get your hp to LT1 levels along with some extra torque to go along with that!

I went with a Miniram from a convenience point of view. It good to say that it is very easy to put on and take off. All you'd need is intake gaskets, vs the 5 other gaskets for a TPI and about 40 more bolts.

 

I used to love the way the long tube runner L98 would grunt around town, made it fun to drive without having to break the speed limit.
Different strokes for different folks.

 

The Miniram will do the same thing. Just fill up with premium gas and bump the base timing up a good 4 degrees.

 

I think it does -- LT1 requires 91 for maximum performance -- the knock sensor lets it run lower but in my experience it feels tired when you do that. Doesn't the L98 run on 87 octane?

 

If you install a miniram and 1.6 rockers, do you retain the stock heads? (I'm thinking the 1989 alum heads weren't too bad). Are the rockers easy with the intake off or do you need to pull the heads/cam?

I'm assuming a chip tune is also necessary. What else is necessary to upgrade these two items (besides gaskets). What's the $$$ required? How much is mileage affected?

Also... Vette engines were described a "bullet proof" when I was younger. That's one of the reasons they were touted (and desired for other applications). Because early C4 vettes can't handle more than 50/100 shot of nitrous, I'm wondering if they are less bullet-proof in our years? Were corners cut in the pistons/block?

Also, how does adding a miniram and different rockers compare to forcing air (i.e., super/turbo charging). This question applies to cost and to results....

Still wanting to know about screw/worm driven blowers. How do these compare to super/turbo charging? Cost/function.

In practical terms, I should also be concerned with seals. Mine leaks some oil (on the exhaust). When it's been up in the air, the initial opinions were rocker gaskets. However, it's not clear to me how to be sure if the intake is leaking at the rear. Even if I do the upgrades mentioned early in this post, wouldn't the extra HP put more stress on 18yr-old seals? This is a big reason, I'm hesitant to start modding otherwise perfectly strong 50K mile motor!

 

If the tuning is done, the camshaft choice will affect the mileage. Closer to stock, better it'll stay usually.

Rockers can be done without pulling the heads.

A 350 chevy will run a long time if cared for, but things like nitrous and other FI can really shorten its lifespan. If you follow some of the nitrous tips on my site you'll probably be happy with everything. The pistons we have are not really meant for use with FI, no.

I'm not experienced with S/C or Turbocharged L98 numbers. Most people are changing cams and heads at the same time, just like most change heads/cam when doing MR/LT1 intake. That throws off the comparison.

Getting more air/fuel in doesnt affect use of octane, that'll depend on the CR's of the engine. Octane is a knock retard additive. You can make 500hp at 8.5:1 and at 11:1, and use two different gasoline ratings. L98s dont all run well at 87, early ones do, but later ones will need to step up a bit. (if you bump timing also, you go higher octane)

 

1.both those options arent very good.
The miniram is going to conflict with the stock cam and heads.

And the Forced induction could possibly wreck the stock parts.

however if your willing to drop the money FI is the way to go The miniram needs supporting modificatoins that would require the dissasembly of the motorto work properly

2.Superchargers:

Centrifugal: Pretty much half a turbo driven by a belt,
Pros: Easy Install, Simple,
Cons: Less Effifient, (Less power per PSI, More power robbed from engine)

Screw SC:
A screw being driven by the belt at very high RPM

Early Screw, (Huge blowers sticking out of hood of drag cars)
Pros: um...... Cheapest, WOW factor....
Cons: Least Effifient, Custom Fabricated intake possible.

Late Screw, (Eaton, Magnussson, ect)
Pros: Most Efficient, (Higher power), Small. Can be pulled off of Factory cars. (3800 SC, T-bird Supercoupe, ect)
Cons: Needs Custom Intake Manifold, Most expensive.

Turbos: (Gods Gift to Man)

Pros:Most Potential, Most Efficient (By FAR), Can actually Boost fuel Economy if designed and driven correctly.
Cons: Complicated and Expensive install, More things to go wrong.

 

 

Lets see.... FI -- forced injection/fuel injection? Easy to confuse. In here, we're talking forced injection (i.e., blowers, turbos, s/chargers).

Are there small blowers that aren't much bigger than a miniram? Since the CR of 1989 vettes are lower than 1960s cars, is their "room" to FI a car without changing everything? That's what I meant by an easy mod without tearing the whole engine apart. I'm guessing you couldn't add much boost since Turbo engines have an even lower CR. Minirams get more air in, why not force air with a fan/blower? Wouldn't have to be huge amount cause it would quickly near CR limits of the motor.... This concept is one of the reasons I'm baffled by the potential of the L98 vs 400+ HP 350 motors! The whole motor must be improved, right? And, that means vette motors aren't as impressive as I thought when I was younger.... Ahhhh. It's all sooo mysterious....

A stock plenum and runners sucks in air and feeds it down the long tube runners. How does a miniram improve on it's function? Isn't it still feeding air into the same ports? Is the problem the severe (90-degree) angle that the runners exit off the plenum (kinda like having kinks in a exhaust)? Or is the tube size too small?

Edit:
Oh yeah. Lost my cheat sheet on upgrades but I was thinking that better rockers were part of the improvements on my heads (89). Don't know if they were "roller" rockers. How to the 1.6's (referenced in here) compare?

 

Let's say your heads flow 200 cfm at .500" lift from 1.5RRs.
At .600" lift, let's say they flow 205 cfm.

Change the 1.5RRs to 1.6RRs. Now you have .534" lift.

Do that on a percentage scale and now you are letting in just 1.5 cfm more air. That's a tiny amount. I don't agree with why people wanna go with 1.6RRs when it makes barely a difference in in performance. Plus 1.6RRs are harder on valvetrain and the valves become harder to open. Your pushrods become more prone to stress. Why would you not just get a cam with more lift? Plus 1.5 is an easier number to work with.

Unless your heads can flow much more on a higher lift, that's probably when 1.6RRs would be worth it.

 

GM did not put the lt1 arrangement together for any reason other than to have a package that fit under the low hood line of the then new 93 f-body. Quickest way to gain clearance was to chop the intake and put the distributor on the front of the motor. Just another GM band-aid.

 

Since the L98 already fit, why didn't they just re-use it? Statements like this seem jaded rather than informative.

 

The l-98 did not fit under the hood of a 93 camaro.

 

Nothing Jaded about it. GM has almost never used a clean sheet of paper approach to improvement from the 50's- the 90's. The LT! manifold is simply an adaptation to suit the need.
You must admit,
300 hp sounds alot more marketable than 245 hp.
I remember the buzz the lt1 created when it was released. 300 hp was quite the number to brag. They did not mention the torque.

 

So do you think the miniram and a few exhaust mods are all that an L98 needs? Especially the later ones with improved rockers/heads?

What was your experience is effort, cost, and benefit?

(Note: my exhaust is pretty close to LT1 breathability after my mods. 2 1/2" front "Y" with lower density, high-flow cats. No real muffers with 2 3/4" catback. If necessary, I can put on long-tubes and/or convert to true dual. But, I'm really thinking top end work would be required first).

BTW: Is an LS1 a shorter life prospect? Since no one has stated differently, I'm assuming the lower end is handling this huge increase with the same (basic) V8 350 design that becomes shaky when exteme mods are talked about here. (In other words, I can't see a discussion about changes to the top end that would result in 400HP without including a discussion about the bottom end). Is their a trade-off between HP and longevity -- even with factory motors?

Note: I'll be honest, I don't particularly pay attention to discussions about modding an entire engine. At that point, it would seem more worthwhile to sell and buy a new setup (like a ZZ4).

gp