sullivan1245

Well I just put new bilstiens shocks on the 94.Now who has some good suggestions on horsepower upgrades.This has the LT1.Ive got the 3:42 performance ratio and it's an automatic.Also has a magna flow exhaust. don't want to do headers. Need some help.75 to 100 h.p. would be nicest has the compression, I thing its needs a cam and fuel delivery help.

topfuel67

75-100 is a lot. That is in the realm of Supercharging or doing a complete rebuild, stroker, cam, heads etc. A cam, tuning, roller rockers will probably get you 30-50 realistically.

drcook

Not 3.42. The performance axle ratio on an automatic car is 3.07. 3.45 was used in some of the early manual shift cars.

To get that much of an increase on an LT1 without headers, you will be needing a setup such as Summit Racing's package.

https://www.summitracing.com/parts/tfs-k304-430-400

Or heads ported by Lloyd Elliot, along with a cam, roller rockers, bigger injectors and a way to tune it, either by having someone tune it for you, or acquiring the componentry and learning how to do it yourself.

A LT4 Hot Cam, 1.6:1 roller rockers and a set of long tube headers will get you close to that also.

Nothing is going to be cheap though.

Kingtal0n

I Know its annoying but before you do HP mods you might want to consider beefing up the drivetrain. For example a converter and a properly build transmission with an SFI flex plate and some stronger hardware. If you aren't planning to make over 500hp I would recommend some lightweight forged wheels to help with the rotating mass, car will move easier, and take some stress off the drivetrain. The differential is a question mark, some will say leave it alone some will say upgrade. I am in the leave it alone dept. Just rock it till it gives some trouble.

Then the engine, maintenance first if you plan to keep it. Wash it by hand, go over every inch and clean it up first. Then make sure its healthy Do a compression test to see where its at, consider the variability between cylinders. If the compression is very good, and the differences are minimal, then I would consider engine mods like cam/head/intake because you know the motor is in great shape already. Otherwise I would be looking at a motor swap to be more cost effective in the long run, and more reliable.

parts wise, If the car is a daily driver, I could would recommend a low lift cam/spring only deal if you DIY with experienced hands, keep the stock heads and maybe even the stock intake, doesn't really matter because you can just go for a supercharger. Some small-ish blower for a ~55% power increase with maybe the cam to help it breath , of course use headers and a decent exhaust, air/air intercooled for safety on gasoline, tune for minimum timing ("mbt"). This will help you skip the major engine surgery and down time, and it will eliminate putting a bunch of time and money into the engine which might fail more easily with all those engine mods on top of it. Maybe even skip the cam, its fine really. And you can always move the blower to another engine down the road or remove completely for recoupe.

drcook

there is a lot in this thread that is not really appropriate for a LT1 Corvette.

smallish blower setups for a LT1 C4 Corvette, for the remaining ones available are very costly. on eBay, more than $6000.00.

blowerworks is gone, the website is non-existent now

read here, has info about procharger

https://www.corvetteforum.com/forums...ink-again.html

so once again, 75 to 100 HP gain is back into the realm of Summit's package, or an offering from Lloyd Elliot

http://elliottsportworks.com/

there is a good chance the OP's 94 has some of the preferred heads for porting

C4 Steck

drcook, I’ve never heard about what you referenced in your last sentence. Are there certain castings of LT1 heads that have more room for port work? If so, any particular date range, and would my ‘95 have such heads? Thank you.

drcook

The 374 or 643 (last 3 digits of the casting nbr) are the more desirable heads as they have more material in the ports to work with. The 561's were primarily on the 96-97 LT1's. The 561's flow best as delivered from the factory.

These nbrs will be in the rocker valley on top the heads.

use this next phrase for a Google search, lots of information available:

desirable lt1 head casting numbers

Mr. Peabody

In post #3 drcook mentions: A LT4 Hot Cam, 1.6:1 roller rockers and a set of long tube headers will get you close to that also.

This is what I had done to my stock 95 A4 about 70,000 miles ago (Stainless Works LT headers, The old LT4 hotcam kit, along with a dyno tune) and I gained approx 40 RWHP on a mustang dyno.

The other thing that I did to make driving the car much more fun was a Yank ss3200 TC.

So if 40 isn't enough then I suggest that you save your money until you can buy a turnkey 450 - 500hp LT1 from an outfit like Golen.
https://golenengineservice.com/lt1-performance-engines/

drcook

is close to 400 at the crank, once all the losses are figured in, which gets the 70-100 hp gain UNLESS the OP was wanting that gain at the rear wheels which is an entirely different ballpark and MUCH BIGGER wallet.

C4 Steck

Good to know thank you.

Kingtal0n

OH my god, this is the lt1 as in 94-96~ optispark engine?

I would not modify this type of engine. I would clean it, maintain it, get your use out of it. But avoid mods at all cost. Use the OEM air intake system and OEM exhaust if possible. Update the opti if that is possible. It can be a good sounding, reliable course, for sure. However

Those engines have a history, a track record of issues relating to their bottom end integrity, something about their compression ratio and piston material science is 'off', ignition system complaints, that make them unfortunetely undesirable and extremely limited in production and value due to myriad issues. If this really is an opti-engine. Sorry I have a habit of telling like it is, and optispark V8 and the 99-00' LS1 (corvette or otherwise) engines are the worst possible engines Chevrolet ever produced. I would save for an appropriate 02+ LS swap, $.029999 almost 3 cents here no disrespect

Sorry about earlier I Get in the habit of thinking 02-12 historical variety, wasn't thinking. A blower is absolutely the worst thing for optispark type of engine. My mistake.

drcook

Tom400CFI

I 100%

Where in the HELL did that misinformative rant come from!?? Oh, I know; Thirgen.Yikes.

Mr. Peabody

Based on 17 years of driving my 95 ........ I'd have to agree ............ there is that strong smell of BS !!

C4 Steck

For sure but it was deliberately constructed that way. I think he was a little miffed for his original post getting picked out. I think the LE1 or LE2 package along with a matching grind would be the most cost effective way to gain the 100 WHP the OP is looking for. Under 2k for intake plenum, heads done right, and a cam is fantastic. The LE2 or 3 package is on my list when I have the time and money, granted humans are still around by that time lol.

Kingtal0n

hmm. I grew up with these era engines, I started with small block chevrolet, how to build your chevrolet david vizard, smokey yunick, 1995 to 1998 was my first series of experiments. From 95-98 I had blower, nitrous, twin turbo application, I wrote software for self-tuning stand-alone ECU before widebands were available at hobby level.

next,I watched Chevrolet struggle with the LT1 design, 95-97. There is a reason it is only a two year production and optispark was never used again, ever, never ever.
If you don't understand the optispark issues then I'm sorry. For twenty years I helped people get out of that engine design. None would ever go back.

What I speak is from memory, there is some issue with the high compression piston and materials science of the LT1. There was also the first time chevrolet used some reverse cooling flow design. It was a time of experimentation and they experimented on the owners.
Those engines would produce 400rwhp successfully but anymore than that the pistons would break. I never bothered trying myself, I speak only from memory of what other people attempted and failed. I was never bold enough to try my luck with optispark engine, when there are 2L Nissan and 3L Toyota engines producing 500 to 700rwhp for 20 years at the same time interval, I switch over to those engines sr20det and 2jzgte and rb26dett, drive the skyline, supra, silvia, etc... very lightweight nimble economical vehicles for the time period.

I've tuned every kind of engine for daily drivers, 1.8L 2.0L 2.2L 2.4L 2.5L 2.6L 3.0L etc... mostly turbocharged. Because all engines work on the same principles I have a habit of treating them all the same, if there is a piston its the same no matter what displacement or manufacturer. However there are notorious exceptions, the LT1 and early LS engines are in the group of notory exceptional. Both have major issues as Chevrolet was trying to figure out how to make a 2jz out of the small block chevrolet. Essentially it took them from 95 to 01 to figure it out, but then they got it. The design of the 02+ LS engine block is similar to the Toyota 2jz and nissan sr20 in terms of it's girdle and pan support, which allows any 02+ Truck engine to handle 600-700rwhp easily as with the 2jz, reliably for 20+ years. I have one in my car right now LM7 200,000 miles 600rwhp daily driver, perfection at last (sig details build). Furthermore the electronics finally smoothed out, resemble the 1992-2002 Toyota/Nissan variants also 'copied', as all vehicles eventually figured out the overhead MPFI sequential EFI and Coil over plug system is robust, ideal. Far far far away from distributor and *cough* optispark. Sorry guys if its harsh but this is my 25 years of building and tuning vehicles for daily drivers, usually 500rwhp is a minimum for me to tune the vehicle at the price I charge and LT1 early LS stuff and most corvette engines I avoid for various reasons, they are not robust enough, I cannot warranty them. I would not tune or trouble with an LT1 or early LS design because it is a fools errand. I will only seek help their owners maintain and clean them.

Tom400CFI

Sniff-sniff....sniff-sniff...Do I smell? Is it?? Yep, it's definitely DOG ****!

Yikes.

C4 Steck

“next,I watched Chevrolet struggle with the LT1 design, 95-97. There is a reason it is only a two year production and optispark was never used again, ever, never ever.”

it was 92-97 (96 for vette). A 6 year period. Plenty of guys running the **** out of stock bottom ends at 400 plus whp that haven’t had an issue with powdered metal rods and hypereutectic pistons. Plenty of guys running intercooled blowers or nitrous even with the stock 10.5:1 compression without issue. Maybe it has something to do with the devilish reverse flow coolant system keeping cylinder temps down. The opti only ever became a problem when folks expected a water pump to last 75k miles and not **** on the electronics beneath or ignore leaking seals or intakes. The opti was further bastardized by companies building cheap remans with sub par sensors and rotors that fly off. The opti is actually quite reliable when taken care of and a quality unit is in place. Why am I wasting my time, my car is obviously a piece of crap because of this damn LT1.

Tom400CFI

Yep, yep.



Yep yep...X2. There is so much conflicted and misinformation in his posts....it ain't even worth trying to address his dog-**** points.

It would be fun to get Diz in here and watch the two of 'em go at it.

Mixednuttz

I'm waiting for him to claim the "cushioning" of additional back pressure from a turbine contributing to better reliability at higher RPMs along with the same two links to nonsense that don't do anything to back the mountain of BS he posts. Next, he'll claim that he's tuned 100s of (fill in the blank combos) and that his tuning "expertise" is highly sought after or that he's examined 100s of Nissan Skylines as they were imported to the US.
I'll say the same thing I said the last time he offered his "advice." OP: if you value your engine, ignore his posts.