Mario65

I have the following and just wondering what it might have cost you guys and what RWHP I might expect on a 91. I was thinking of just doing all 3 (injector port/heads/cam)instead of piece meal.

Lighter flywheel
4.10s
Stainless works headers
B and B exhaust and x pipe
SGC tune

I think it rear wheeled around 37x hp

cv67

Pays to be able to port your own.
Would cost me gaskets and fluid thats it.

hate to have to pay someone to do all that.

Paul Workman

Stock RWHP should be in the 335+ on a 90-92

"Lighter" FW? Assuming a Fidanza, according to dyno runs done by Marc Haibeck, you "gain" 15 hp on an inertia-type dyno on a 500 hp package. A stock motor might see 13 (doesn't rev as quick).
SW headers = about 25 ish
B&B w/ X pipe: that depends on which B&B. Newer are more restrictive and choke hp gains, but prolly safe to guess around 10+
Tune is usually worth (again, according to Marc's data) about 10 hp

Multiplying the gains by .85 (drive train loss) and you're in the 380-390 rwhp range.

Top end P&P is good for about 35 fwhp, or 28 at the wheels putting you in the 400+ rwhp club, depending on how/ who does the work, which brings up the point-



All that, except the tune perhaps, can be done by anyone with reasonable mechanical ability. And, the LT5 will love you for it!

Now porting the heads and changing cams and you break into another level of expense and complexity. The motor has to come out, and unless you have a model to go by and are good at or know someone very good at welding aluminum heads, I wouldn't recommend it. (But, then again, it is very rewarding - and sometimes frustrating - to do them yourself too.)

Using the "FBI" patterns, and stage-I intake only (stock exhaust is plenty good at this level), and proper cam timing modification, and rwhp jumps to around 450 - give or take. Anything you can do yourself will cut the costs. But, to hire it out, the head work, valve job after, gaskets, cam regrind, lifters, assembly and timing, plus getting the motor there and back, and you're somewhere between $6-10k for 50 more whp or 450 ish total. That's about $140-200/ whp. Throw in the plenum/IHs and you add another $700-1200 to have it done.

Some hp is cheap, but a "500" package gives you a bullet proof motor that idles like a stocker and just loves to stomp on all but a very few contemporary "sports" cars out there!

P.

FU

There's almost nothing on a LT5. That's as satisfying as a well done top end package. Money well spent.

Graybeard ZR1

I've always wanted to have the top end on my 91' done, and have long ago installed all the other equipment you originally mentioned.

My attitude is that if there is a job on the car that needs doing, and I have the tools, I'll do it myself. But if it's a big job, that I need to get tools for, or it's a job that I will likely do only once like porting and polishing, then I'll pay to have an expert do it.
This is not a "repair or replace" type job, and I'm sure that there are a lot of do's and don'ts involved. So if you're not trying to learn a new skill that you can put to use in the future, why learn a skill you'll unlikely use again.
Bottom line, much as I like to play with a grinder, I think i'd rather have my top end done by a guy that has done a dozen of them, and can max out the improvement rather than do it myself and have my first effort be less than the best.
After having said all that, I do respect anyone that tackles the job himself. More power to ya.

A26B

As you have seen, there are several ways to do this.

Greg VanDeventer was part of the LT5 production team at Mercury when the engines were built there, and has been doing LT5 porting for over 15 years. The safest way to insure the outcome of the job is send him your parts and have him do the entire top end.

His prices may have changed, but was $1,900 for heads, injector housings and plenum. To increase the throttle body to 63mm & machine, contour & polish the air horn was $450.00.
About $1900 ~ $2400 + shipping & labor to R&R the heads

The lighter, Fidanza flywheel is a hit/miss success. it does result in faster revving, but the transmission gear rattle that frequently occurs, causes some to put the heavier, stock dual mass flywheel back in.
Flywheel & new clutch without labor will be about $1,000., + labor


4.10 gears are very popular and does increase the driveability. 4.10's are an the generally accepted maximum in differential reduction, with 3.73 & 3.91 being popular as well. Numerically lower gear & more horsepower equals more wheel spin in 1st gear.
About $1,000 with labor.

SSW headers with B&B x-pipe system, is here again, on the ultimate end of higher performance. That combination is the best for the most power. However, B&B is too loud for some.
About $2500, + labor

Tuning.... for the best results, tuning should be accomplished on the dyno. Package tunes will get you close, but may not reach the optimum because fuel delivery and other factors specific to your engine, are not absolutes. As such, they will usually leave a little on the table by running on the conservative side of spark & A/F ratio.
About $300


The package you describe will definitely get your attention.

MRDZR1

I have almost this exact package on my car (Mark Haibeck chip not tune on the dyno...I which) and it gets everyones attention when I give them a little 1,2,3,4 gear shifting ride at the race track.

My next step will probably be the Bill Boudreau ZF balance & blueprint to get rid of the ZF rattling.

Mario65

I have everything I mentioned except the heads and injector housing port, and cams.

I was quoted a price for the same which I thought was high in comparison to LSX and Pontiac H and C work I have had in the past. I understand the extra cams I didn't figure having to pull the motor to do H and C's apparently.

Just trying to compare and get some support to justify the cost.

377RWHP to 450RWHP is definitely something that I want. I want to keep a stock look so boost and spray are out of the question. The car is way to o nice for that.

blr33439

I have the a 368 with stage 1 cams in mine that dynoed at 470whp. Subtract the stage 1 cams(and $4k) and you are at 440-450whp. Go back to a 350 and you are at 420-430whp. If I had to pay for it myself, I would probably stop at the 350 with full porting of the heads, intake etc.(420-430whp). Cams are really expensive for the gains seen. You might want to give the NOS more consideration since there is a lot of room to hide it under the intake. If it was my money for hp gain, I would go with NOS. 470whp is out of control on the street with standard tires. With NOS, you can use the boost when you want it.

As far as boost goes, you are limited without breaking into the bottom end since these engines have such a high compression ratio. If you can do it yourself, the cost would be reasonable, but a lot of trouble pulling the engine, etc. I would consider boost if I wanted more power(I really thought I would), but after driving the car it just seems unreasonable. I always wanted a 1000hp twin turbo vette until I got the 560hp vette. 1000hp just seems unnecessary now. With the cost of upgrades on these engines, boost may still be a cheaper way to hit your hp goals.

Mario65

So you did your own port work and the only significant out of pocket for you were the cams?

If you were to pay for the heads, cams and intake/injector port whats fair?


thanks for the info and advice.

470 is wonderful. That would definitely keep me away from considering a c5 or c6.

Graybeard ZR1

Here's what I consider fair. Marc knows how to do it right.

http://zr1specialist.com/HAT%20Web/p...%20Paths1b.pdf

Mario65

thanks graybeard thats excellent info. That answers all my questions and gives me a dyne to see it

blr33439

I bought my 90 with the fully built 368 already done. Some points I will make on what I have seen on mine. Make sure you replace injectors with ethanol compliant injectors(just replaced mine and it did make a difference(the secondary injectors were only a few years old and already bad)). Whoever ported the plenum made the walls too thin and they had to be welded to fill the holes that developed. If you want to tackle this yourself, be very careful. I wouldn't even consider doing the heads myself on one of these. The best improvements on these cars seem to be exhaust, intake(air filter, etc) and then everything else. I have 4.10 gears on mine and it just doesn't make sense on street tires. If you have the money, I would pay someone with a good reputation. If I had to negotiate every performance dollar on this car with my wife, the list would be:
Exhaust
Intake
Plenum/Throttle body porting
Head porting
Nitrous
Cams

One more note: I am finding broken small parts, cross threaded bolts, etc as I go through my car. Be careful who you let work on yours.

One more thing: Both Corey and Marc were very quick to respond to my questions. I would give them priority if I was going to have more work done.

lgaff

Pete over at the ZR1.net does a great job on mods, has access to cams, great head port CNC porgram, and he tunes cars well. He recently reworked one of the original blackwidow car and it runs better than ever.

Price is right too. He has a full garage and access to parts....

If you want his info, PM me his car runs 11.2 @129 with a 350...as good as the big blocks

Mario65

Yea I found those videos the other day and that car runs great. Very impressive and enviable performance. 129 is moving. I sent him a pm at other forum. Ill see what he says. I got a good price from SGC I just want to be sure theres not another option and that the price quoted is comparable to what else is available.


thanks for the headsup.

Aurora40

FWIW, to your original question, I don't believe there is much, if any, cost difference in going piecemeal for some of it vs going whole-hog all at once.

I would suggest that porting your intake and injector housings would be a good next modification. It is much much cheaper than heads, and delivers about the same amount of improvement (by which I mean, ported intake vs stock, and ported heads and intake vs just intake). You can decide if getting that level of gain a second time is worth the extra cost of the heads.

I would also suggest, you can get the plenum/IH's done pretty cheap (or at least a lot cheaper than they used to be). But if you are thinking of doing the heads, you may want to have whatever shop you'd use for heads do the plenum/IH porting. That way they will be happy with the level of intake porting when it's time to do the heads.

I will also toss in that Marc H did my intake/IH's and TB. I had no regrets, and the improvement was both noticeable and fun. Honestly to me that gets the engines running how they ought to, which is to say pulling hard to redline (stock drops a bit in the mid/upper 6's). More on top of that is gravy, though, and I think heads car would have been awesome.

cvette98pacecar

Here is the best advice you are going to get. Leave your current car alone, dont do a darn thing to it. For what it is going to cost you to build a 500HP tuner you can almost buy a car that is already complete and bullet proof.

Paul Workman

That comment made me chuckle. Keeping the stock look, (and idle) makes for a killer "sleeper".

Looks and almost sounds stock (a bit throaty due to "Pete the Greek's" cam timing and the headers). (This video was taken when it was 19 degrees outside, hence the water vapor exhausts. )

Anywayz, here's a peek at a "500" package with stock cams and bottom end. It has been very rude to many C5s and C6s!

http://www.youtube.com/watch?v=y1YFa8ruh8A




P.

Mario65

Thats a great car. You should be proud of it.

Mine already sounds wonderful. I have had some bad cars and I have never had a guy roll down his window and tell me that my car sounds awesome like one did last week. I love to hear it and can't believe people are moving them to throw money at a c5 or c6 especially when they are modded. To go up to 350 rwhp won't be as much as I thought initially. So I am thinking about it rather hard. It would be nice to pick a fight with a new zr1.

cv67

350rwhp will keep you entertained for about 10 min too much out there that would take ya.

At least get headers, port the intake, IH and a good tune. Thats a start.

Get someone whos qualified and a good track record with porting.
Too many hack jobs out there these days...and lots of over porting being done. Bigger is not always better.