Low on power?

[1990 quasar blue]

I was reading through some threads and seeing some numbers of cars with similar mods. LocoBob's old 91 making 374rwhp, another guy making 386. I have ported plenum and injector housings by G.V.D., Flowmaster exhaust, HAT PROM, open lid, and a Coplon duct. The best the car has done is 355 rwhp and that was about a full point lean. I had it fattened up a little and now it's down to 350. Could this be a cam timing issue? The car seems to run good and pull hard but, the numbers just don't seem to be there. Any thoughts?

TIA,
Mike

[Z Factor]

I was reading through some threads and seeing some numbers of cars with similar mods. LocoBob's old 91 making 374rwhp, another guy making 386. I have ported plenum and injector housings by G.V.D., Flowmaster exhaust, HAT PROM, open lid, and a Coplon duct. The best the car has done is 355 rwhp and that was about a full point lean. I had it fattened up a little and now it's down to 350. Could this be a cam timing issue? The car seems to run good and pull hard but, the numbers just don't seem to be there. Any thoughts?

TIA,
Mike

Mike,

Assuming their numbers are accurate, don't most of the cars you are referring to have headers, no cats, an x-pipe, and a 3' exhaust like the B&B tri-flow? Almost everyone trying to hit the magic 400rwhp without cubes or the juice goes that exhaust route along with top end porting.

:cheers:

[WB9MCW]

1990 quasar blue my gud buddy zr1pete does p&p and exhaust mods to ZR-1's in the chicago area and i am sure u could benifit from e dicussinos with him. he is a zr-1 fanatic 4 sure and a great guy. he will get u too the 400 mark,, he told me anytime i want to let him do his majic to my Z he could get me there!!! here is his email and ill let him know of this post. he is a member of zr1net/reg and assists me at corvette mech. as one of the mech's i consult to solve ?'s we get there from zr-1 owners!!! :handshak:

[Locobob]

Could be a lot of things: Production power level variation, Different dyno, Test conditions, something amiss in the motor - dirty air filter, plugged cat, etc etc. Incidently my old Z made 355rwhp with Power Effects exhaust and a DRM chip. Power climbed to 374rwhp after porting the intake. To contrast Jeffvette made 340rwhp with Corsa exhaust, about 355rwhp with intake porting and about 390rwhp after adding headers to the mix. Every car is different and a lot of factors can affect dyno numbers. I wouldn't stress over it too much.

[1990 quasar blue]

Thanks for the replies.

ZFactor, I don't think they had headers, or at least LocoBob didn't. As far as 3" exhaust, I don't think it makes a huge difference with stock cubes.

WB9MCW, I'm familiar with Pete from the other forum, and he is very knowledgeable. As it stands I have everything but the headers. Maybe this winter.

LocoBob, The car was a little weak from the start. Only 320/320 but, that was stock right down to the eight year old plugs. I'm not worried, it still does pretty well for a fifteen year old car. I just keep wanting a little more.
:cheers:

[Z Factor]

ZFactor, I don't think they had headers, or at least LocoBob didn't. As far as 3" exhaust, I don't think it makes a huge difference with stock cubes.

I just keep wanting a little more.
:cheers:

To get up to the levels you mentioned it would be tough to do without headers and a good exhaust. The 3" exhaust with x-pipe does not make a huge difference over other non restrictive aftermarket systems, but it does help. With our cars, every little bit helps considering that major power increases equate to major $$$ beyond simple bolt on's.

Like Locobob said "every car is different and a lot of factors can affect dyno numbers".

As to your desire for a "little more", we know where you are coming from. My best advice would to talk to a respected tuner like Aaron or Mark. They are both generous with their time and advice.

:cheers:

[rkreigh]

350 is actually not bad. dynos vary a HUGE amount depending on which one, correction factors, ect. the "dynojet" is pretty much the standard.

the real question is how does it run MPH at the track as it's a bit easier to gauge performance than dyno queen numbers.

I've seen some cars that dyno 340 post up some pretty impressive MPH.

alot of the "porting" isn't very agressive and as you already pointed out, you started at 320 which really isn't far off.

plus or minus 10 hp is pretty minor considering the various correction factors and dyno readings.

don't get too hung up on numbers, go flog it and see what she'll do.

[Aurora40]

My numbers aren't any better. This is on a Superflow dyno at Tony's Corvette Shop in MD. My car with ported plenum/IH's (and new injectors, tune up, etc) made like 327hp. After swapping mufflers and resonator (described in this month's HOTB newsletter) it made 350hp. The car has not been tuned though, it has a Haibeck chip he shipped me along with my ported top end.

My hope is it's the dyno that reads low, that's what the dyno operator mentioned as well when compared to a Dynojet. But whatever, it makes what it makes. The best 1/4 time on a summer NJ day was 12.7@114 with my meager driving skills.

[1990 quasar blue]

Thanks Ron, I'd forgotten all about this one. I've since sent the intake and injector housings out to Jeff for PC. While there, Lococbob did a little more port work. I've yet to go back to the Dyno but, the car does feel a little better. The car has been to the track once and they cut it back to 1/8 mile due to wind. It consistently ran over 89 mph with a best of 89.43. That being said, I've had people tell me that the only reason it trapped that high was 2.1 - 2.6 60' times. Everyone there was complaining about traction as it was pretty cold.

[1990 quasar blue]

Aurora, I think we both need headers and a Fidanza. Or at least a real time dyno tune.

[GrayZ]

i really don't know what the numbers should be...but many
agree...they really vary...so with that in mind..my
car is stock except for headers...at it pulled 353.2 at Bowling Green
last year..i have added corsa exhaust..and i can feel a difference,
more pull ..quicker...since...so...i hope the new catback exhaust
raised the horsepower..6 or 7 horsey's ...next up for me...
will be a haibeck tune..gears...and next year..a HP upgrade..

[WB9MCW]

I PUT A Fidanza IN AND I REALLY LIKE IT PLUS THE CERAMIC RACE CLUCH FROM CAROLINA CLUTCH IS THE TRUE SECRET----

http://www.carolinaclutch.com/

http://www.carolinaclutch.com/images/Header.gif

[1990 quasar blue]

Keith, those numbers look good to me. It seems like the early 90's all do well.

Bryan did you order it as a balanced set? Do you have a part #? A guy on ebay was selling the Fidanza for 360.00. Seemed like a good price.

[WB9MCW]

yes I got it as a package deal from them. I do get the "rut-rut-rut" syncro rattles but it is worth it IMO--My mech and best friend said it would drive him nutz--but he did admit that it hooks great now--I did the beam plate too---Drop the hammer at 3,500 and hold on + my custom perf chip helps keep it cooler and 1-4 cags gone and rev limiter bumped up a tad too so overall a much faster ZR-1...Chirps in third like it used to do 2nd--get a decent "squak" in 2nd now--and burns rubber all the way through 1st but still getting good traction on my Dunlops---very impressive for stock exhaust and a fairly stock ZR-1---its enough for me! I figure my 12.8 sec QM is at least a 12.3 to a 12.5 now but I have never confirmed it at the track. Best part is I can let it idle in the hot summer sun on a humid 90+ and the temp never gets above the 210 mark (used to go all the way to 230f) as soon as I drive away and go say 40mph or better for a mile it goes down to 190f---used to stay at 230f and never go back down. Stupid the way they had it set so high for the emissions from the factory---I bought a "Big Mouth" air deflector but never put in on since the chip did the trick---I think my fan kicks on at 180f now vs the 230f stock chip crap. I know almost all go the header-hi flow cats-and b-n-b pipes but I like stealth and the stock is not that restrictive IMO and still has a good enough sound at WOT for my likes---and keep the coppers from hearing me b4 they see me---big + IMO. My 84 had a very loud note and drew too much attention---part of what I luv abt the stealth stock sound ZR-1 is the look on others when I do stomp on it be it a passenger or the guy in the other car I just waxxed!!! LOL My fav is the 7000+ rpm shifts and the hood going up and down abt 3" at shift change. A regular vette just does not do these things....Long live da KOTH...

[Aurora40]

Aurora, I think we both need headers and a Fidanza. Or at least a real time dyno tune.
Hopefully at the end of March or early April I'll be getting the headers and tune. I want to hear the flywheel first. When I first bought my car it had a rough idle and the gearbox sounded like crap. Not sure if I'm down with that. I have been thinking 3.73:1's might be a good move, but we'll see.

[WB9MCW]

Hey A make no doubt of it it does make a lot of noise ---but to get rid of the large heavy flywheel---well to me it unleashes the true beast of the lt5 and the rev's build so fast you really have to relearn how to shift and be very precise...like a whole different car. I'll take the noise any day over the slugglish stock unit. plus the only time i hear it is at idle when the clutch is not held down and when you load and dog it in 1 and 2 and are luggin ur motor---but folks do ask what the hell the damn noise is when they ride with you---i tell em it is a noise of high performance---they usually shut up after i unleash the beast through 3 gears...the ceramic race clutch is fantastic IMO