Hey guys.... I am a C3 guy, but I am working on my sisters 94 Z28 LT1. Just had the engine rebuilt and I had the heads ported, polished, port matched ans 202 valves put in.... So far that is the only mods. I would like to know what are some other mods that I can do that will add some HP.... And not talking headers, cam, and exust... kind of want to stay around the throttle body, chip, and the like... and suggestions? Thank you, Paul

 

Paul, unfortunately those cheap mods are basically worthless. Save your money for real mods like 1.6 full RR's, or a dyno tune.

 

I agree.

The cam, headers & exhaust will really wake up an LT1.

Then the dyno-tune would be the icing on the cake.

Also, give Jon at Fuel Injector Connection a call. The Bosch Design III fuel injectors work. He can work up a good price for you.

Use the "Search" feature here to say what other have said about Jon and his injectors.

Save the Wave!

 

so you guys are saying the chip mod and throttle body mode yield little to no positive results?

 

Chip and throttle body really aren't going to work, until you go internal and mess with stuff. A bigger throttle body on a stock engine isn't going to change much. A chip at this point should really just need some fine -- and real fine -- tuning to make everything perfect.

 

A lot of guys think a TB up-sizing doesn't gain you anything, yet CorvetteMagazine's dyno results differ. 7 ft lbs and 14 HP when moving from a 48mm o a 52 mm.

The results are posted on their site, at least they were when I found them a while back.

Basically here's what they did:

Dynoed a stock LT1 - 293/331

Swapped to some ported heads but still with 1.94/1.50 valves 320/339

Removed MAF screen and installed TPIS air cleaner 327/342

Swapped 48mm to 52mm picked up another 7 fl lbs and 14 HP

So in that sequence, there was a definite power improvement.

Can't argue with 14 HP and 7 ft lbs for only $300 or so cost. I've seen dyno results where over $1,000 was spent on a full exhaust upgrade that only showed that amount of power increase. (i.e. Thunder Chicken, an LT1 "F" body)

I may still have the link to the site and will try to track it down if anyone's interested.

Jake

West Point ROCKS!

 

I personally don't know how much a trust those articles Jake.

First off, I have no clue what dyno they used but a stock LT-1 will not make 291/331 on a respectable dyno. My bud's stock LT-4 struggled to make 300/300 in stock trim.

291rwhp/331 rwtq is "about" 345hp/400tq at the flywheel, and after driving a few LT-1's in stock trim there is no way they make that kinda of power.

It might be a good atricle in regards to what "possible" gains might be had, but I wouldnt want an uneducated reader to think that's what power there car is making because it isn't........

I think you understand.

 

I do think that you can run across a "runner" on the dyno.

My 92 with only a Corsa Catback and SLP cold air setup slapped down 3 runs making 278HP /305 Ftlbs.................. through a A4 .....................with 115k on the clock.




But anyway with the head work and larger valves you would see some good numbers by ditching the stock exhaust / manifolds. However I do see that you want to stay away from that and a cam swap.

I guess at that point you could do a 52mm TB however I doubt you would see much if any real gain for the money without the rest of the combination.

 

boy.... sure do like my 400HP/tq 383.. seemed easier to make, but not quit smog legal, like i have to make this 93....

Ok, so if i change the complete exhaust system, and the TB and chip..... can I get say...... 45 more ponies?

 

On a stock C4 TB/chip and exhuast mods offer minimal gains; however, the F body has a lousy exhaust and exhaust mods will help, but for 350-400 rwhp you're looking at heads/cam/valve train/exhaust and a good tune.

 

Yae... I understand the standard upgrades... I have rebuilt several engines in my vett and jeep and other cars. What I am less familiar with is the LS1 type of engine and its own peculiarities for HP gains. But yes exhaust would be possibly different on a Z28 and more restrictive, so maybe a set of headers and new system would be the best next step...just looking for 300.... that car will never beat my C3.... never

 

As in the earlier post about the TB, you failed to mention one very critical point! There was ALREADY mods done to that LT1 before they slapped on the Throttle Body.

You will see (repeatedly) that LT-x's don't do well with JUST a TB upgrade. It will yeild next to nothing. In fact, your throttle response will "suffer" slightly (maybe so minimal that you wont nice).

the above engine had work done, and therefore, the builders realized that the TB could possibly be their next restriction.

roller rockers seem to be a good upgrade, but you'll end up needing better valve springs etc. This "can" be done with the engine in the car (on y-body) with the right tools, but the F-body cowl panel might get in the way.

headers are relatively expensive, but the two-to-one style of the f-body is definitely resitrictive. "true duals" will yield a better gain.

the cam is a "great upgrade", it's just a nightmare to swap on these engines (i.e. all the components that need to be removed just to access the cam).

here is what I suggest (if you don't want to crack the engine block open for cam etc).

-have the intake manifold ported (a little bit of a "creative" mod) by AI or LE
-have the TB opening ported out to 52/58mm at the same time
-purchase your 52/58mm TB
-get magnum or gold series 1.6:1 rockers "if" you can get away with it while the engine is still in the car
-full length headers (power increase is minimal, but I wouldn't even bother with shorties)
-get a shop to fab up "true duals" 2.5" is stock on y-body lt-x, or go 3"
-Electric water pump (frees up some power)-
-"cold air intake" -do some research to see which one has shown true increases. I believe the ones that replace the stock plastic components with alloy cast pieces have shown increase in the f-body forums.
-hi-flow cats
-dynotune


-all else fails, nitrous seems to be a relatively plainless way of getting decent power

 

Nitrous.

 

Those are flywheel numbers not rear wheel. The article is entitled "LT1 Power Play". I'll track down the link and post it. Then those who read it can decide if they believe the results or not.

Jake

West Point ROCKS!

 

Here's the link:

http://www.corvettemagazine.com/1999/oct99/lt1/ltp1.asp

BTW, my Engine Analyzer Pro simulation programs shows similar results; 12 HP going from 48 to 52 and another 8 HP going from 52 to 58mm.

Jake

West Point ROCKS!

 

Here's another point from personal experience;

When I moved from a 48mm to a 58mm TB, the engine 'felt" dramatically stronger. It accelerated much stronger/quicker. We're talking Seat Of the Pants.

Why? Due to the larger bore of the 58mm TB, for every incremental movement of my right foot on the accelerator pedal more air - as compared to the 48 mm TB- enters the engine.

Using the same pedal pressure that I had become accustom to when I was running the 48mm TB, the car would blast away from a standing position, like at stop lights, and I felt like Speed Racer. I've posted on this a couple of times before.

It was so dramatic that I finally decided I couldn't live with it, so I traded my BBK 58 mm TB with a Forum member for his 52mm. My car then became much more managable and I was better able to modulate the throttle.

According to a program I have that does such things, the calculated airflow CFM is:
48=564
52=693
58=857

Bore Diameters in inches:

48=1.8897
52=2.0471
58=2.2834

Anyway, this is just info I'm passing along.

Jake

West Point ROCKS!

 

You just eliminated the 3 things it now needs the most.

 

As stated the F body exhaust is restrictive to say the least.Hence the loss in power from the vette to the Z-28.Headers and a cat back with an improved Y pipe would make a huge difference.Start with the Y pipe and cat back if you don't want headers.I don't think intake mods will help until you address the exhaust.
Another option would be gears and/or a stall converter.

 

Think im going headers and true duel exhaust...

Remember... I have done a lot of head work already... porting, polishing, port matching and 202 valves....

So, any already prefabbed Header, true duel exhaust systems out there?

 

man, you'd probably be better off asking the f-body guys. they would be a serious wealth of knowledge.

I think since you've gotten the heads ported/polished/etc. that this would be the oppertune time to install complementary mod's

stall converter, electric water pump, shorter rear-end gears, headers, true duals, intake, Tb... this should be a fun mix of parts.