GREGGPENN

I've heard bits and pieces over time about what the differences in these two motors are. And, I'm not talking HP/Torque. I'm talking about design.

What did they do to get 50 more HP out of a 350? How about newer models?

I've also heard recommendations to put a mini-ram or similar on an L98 to wake it up. (Of course exhaust manifolds have to go as well). So forcing more air thru it helps. Certainly makes sense since the compression is so much lower than 60's cars.

60's cars had like 10.5:1 or 11:1 compression. Even more... Ours is something less like 9.5 (don't remember this minute). Obviously putting something like a 50-100 shot of nitro is suggested, but I don't like that idea. What I do like is the plenum and long-tube runners. They're what makes an L98 look like it should run with (or better) than an LT1. Do they make a better intake that maintains stock appearance? The miniram is too boxy looking and takes something away asthetically. Plus the intake on an L98 looks like it should be more impressive -- if you could just force more air into it. Sure, supercharging is an option, but I don't get it.

How come the LT1 and newer 350's are soooo much better? If it's all about valves and getting more air/fuel in, why doesn't that require higher octane -- like higher compression did? Why is the intake (plenum & runners) on the L98 really the constriction? Does it really just look more impressive than it is?

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?

It also sounds like every single upgrade has a flaw and/or isn't a huge benefit -- especially for the price. Is it the actual design of the internals (valves, cam, etc) that make new motors better? If so, why wouldn't everyone sell their motor and start with a new one. After all, lots of people want a vette motor, right? And, I have to ask why -- if they've become so unimpressive!

gp

rocco16

Well, more sophisticated engine controls had a part to play. Better fuel injection was some of it....as well as optimum ignition timing.
Head design is a constantly-improving science.
Better cats surely enter in.

Then, there are the usual go-fast items: more aggressive cams, better- flowing intake/exhaust systems, more compression, bigger valves, etc.

The power put out by modern V6's amazes me. But, then, I remember living with 230cu. in. Stovebolts.

Larry
code5coupe

EvanD

I think you've answered your own question. Better head flow, exhaust manifold flow and fuel injection give the LT motors more power. More computer design allows for small improvements that add up to more power output and smaller parasitic power usage from things like the distributor, water pump, etc... The water pump itself mike not be the power savings but the force it uses to push the coolant through could be less saving power...

The newer motors make even more power for the same reasons. Design work has made 4 bangers that give really high performance especially when you compare a 1 liter motorcycle motor to a 1.8 liter car motor. Greater than 100hp per liter is pretty common on motorcycles. We are getting there now with the cars. Wait till we're getting 160+hp per liter, stock from the factory, like the newest sport bikes, that's over 900hp from a 350!!!

BrianCunningham

LT1's have 10.4:1
LT4's have 10.8:1

Reverse cooling and more precise engine control allow the higher compression which equals better power and better gas mileage.

vader86

Primarily the intake design and a better exhaust system.

LT1 heads are better, but not extremely different. They certainly flow better but the difference in port volume is rather small.
Camshaft is really not that different, slightly more lift and duration on the intake side. Cooling change and timing will help to raise the CR, which helps power.

Its the TPI intake that really squashes its HP rating, it just dies where the LT1 intake feeds the engine quite well. LT1 is also not heavily restricted on the exhaust side either.

86_RedRider

intake (probably 80-90% of the 50 HP increase).

yes improved heads and cam, but they wouldn't work well if the restriction was in the intake.

does reverse cooling really add any significant HP?

A miniram is basically an lt1 intake.

zr1fred

I'd say exhaust is the biggest factor (but not by much) . Reverse cooling helps keep the combustion chambers cooler with the higher compression. But with the newer engine control systems higher compression (cheapest horsepower) is becoming standard on almost all engines.

cv67

Air/Fuel management (EFI)
Roller cam
Better cylinder head design=more power, more efficient, more MPG.
Doubtful. May help the combustion process tolerate compression a little better though.

corvetteronw

Somewhere I have the address of a company that modifies LT1 intakes to fit the L98. Can't find it right now though.

vader86

No, but it allows the CR to be raised, which itself does raise HP output.

GREGGPENN

What's an L98? I'm thinking there's a diff between L98s and high HP motors of the 60's. Was is 13:1 back then?

Does this discussion include why 350 motors are now even better? How are they doing this without creating the need for high octane fuel as required in the 60s.

If fuel management (air & fuel) is the key, it is because there's more of it, a better mixture (combustibility), or something else?

I saw where a 400 motor circa 1970 was originally touted to have close to 400HP. I know the ratings (methods) changed and that same motor became a 250HP motor afterward. My '89 is also about that. Does that mean my 350 has about the same HP as my '68 GTO had? I'm thinking the vette has less weight and I know it has less drag, so it that the only reason it feels faster?

Someone who saw my car (hirise hood) suggested I put a worm-driven blower under it. W... the )(*&^(*&% heck is that?

gp

GREGGPENN

List the payoffs.... How much more HP/torque? What else needs changing out?

vader86

The website that modifies them is on my site, as is a writeup of what was changed on one particular car. As I've said, if you look at the two engines you'll get a decent idea of what you get by throwing an LT1 intake/MR on a stock car. You wont get quite the 300hp, but 280ish wouldnt be out of the question. (after a chip tune)

The reason why LS engines are making their power is the head design, and their big change compared to us the valve angle and port volume (HUGE).

Older motors need more octane, and some of the power claims were inflated by the makers, some of it has to do with the gross v. net rating system (some make alot more than their rating) and those cars also have less efficient drivetrains in most cases. EFI can also make the engine more efficient over the whole rpm range, but that doesnt necessarily affect how fast it is.

GREGGPENN

30HP from changing the intake hardly seems worth it. $$$ to get 10% gain? I have to assume LS heads can't be put on an L98 block either...

Obviously, an engine is an air pump. For it to be efficient, it needs to draw a mixture in small amounts to produce efficient power. At the same time, it needs to pull large amounts to generate lots of power. The heads are definitely the complicated portion of that entry point. (The intake and injectors are just pathways to get air/gas to the cylinders and I'm guessing they haven't changed much).

It does seem that heads could make the biggest difference. And, that probably requires a different cam to drive them. And, that means a different motor....

Still wondering what a worm-drive blower is....

rad928music

rocco16

You assume correctly. The LS is a completely different engine.

Cam doesn't drive the heads...heads aren't driven... by anything.

So am I....
Never heard of a worm-drive blower. Maybe the guy was thinking of the screw-type blower?

Larry
code5coupe

GREGGPENN

Put a smiley with this statement and it's O.K. I'm guessing you think the valves are somewhere else?

For a guy who has to have the exact, correct term/phrase, I'd say you're probably guessing right....

vader86

Just as a single mod, no. I dont look at it that way however, I look at the HP potential.

Between L98 and LT1 heads? nope. Look at the specs, both are in links off my website.

Between Gen I/II and III/IV, yes.

30 is only a figure, it could be 40, I just dont think it'd get up to quite 300. The differences are small but there are several of them that contribute.

GREGGPENN

So... It's not particularly easy to describe why motors have so much better output today. Techology is too cheap an answer.... Better heads, valves, etc... doesn't make it clear either.

Is it safe to say the 350 V8 of each era were really at/near their potential? And, that major design changes were required to create significant gains.

If so, those who say we were cheated by GM just don't realize the accomplishment of the engineering of the times.... Or does the whining come from the lack of attention by GM engineers? That is, the attention necessary to create a 400+HP 350 -- in an era where safety and mileage started to become so important?

I guess I'm also surprised that the basics of a V8 have really changed that much as to create such a dramatic change. Are our engines really THAT different than they are now?

The answer must be yes. To those who say so, what would you site as the single biggest reason engines are better. "Technology" is too general....

zr1fred

Unfortunately, technology is the answer. Todays engines are systems, you can't really change one thing to significantly alter performance. It could be argued that untill electrical fuel injection the small block pretty much peaked in 1964 with the 327/365 hp engine. 2.02 heads/11:5 compression/ 2.5 inch exhaust. Kinda sounds like an LT-4!