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I agree, you got some real douchebag answers. Not everyone on here is like that, obviously.
I have always been puzzled watching shows like Engine Masters when they go and build a VERY basic small block and throw it on the dyno...BAM....400+ hp. LT1 is a fuel injected "high performance" engine in a sports car and its only 300hp ?!
And that's out of a carbed motor. I like watching but I think they are a bit out of touch when they put that and on the dyno and we're disappointed with only 400 hp. I'm sure most of us here would be happy with that.
I have always been puzzled watching shows like Engine Masters when they go and build a VERY basic small block and throw it on the dyno...BAM....400+ hp. LT1 is a fuel injected "high performance" engine in a sports car and its only 300hp ?!
Well....You gotta get your numbers right, and then everything makes more sense. You're talking GROSS vs. NET, and that's not a legitimate comparison. That Engine Masters "425hp" engine is only going to be about 330 hp or so, in a car. The "high performance" LT1 is instantly 350 hp when you take it out of the car and put it on an engine dyno w/no accessories. 360 hp w/no water pump.
The dyno shop wisdom says that there is roughly a 15% penalty with a chassis dyno vs an engine dyno. That number gets closer to 20% with an automatic. The number doesn't really matter as long as it puts you back in the seat when you punch it and it beats your buddy's car.
True...but note that I didn't even mention chassis dynos. I was talking engine dyno's. One measuring NET (what you get in the CAR) and GROSS (what you get with no accessories, and everything optimized).
EngineMasters' "425hp" engine, is going to make about 330 hp int car...and if you throw that car in a chassis dyno, you're going to get ~300 RWHP or so. Now all of the sudden, Engine Masters' big numbers don't looks so big.
FYI, I think the 15/20% thing is outdated. My LT1 was about 9% lower than it's crank rating, at the wheels. Same with my C6.
What is lost really will depend on the application. The LT1 C4 has a better exhaust than the F, B, or D bodys along with the l98. The air intake is another are, the gen 3 Camaro had a better design air intake the the firebird due to lower hood line. It was supposed to have been 5 hp. IMO the LT C4 has among the lowest application based losses.
i would say your knowledge is about about as good as anyone on the forum but a 9% drivetrain loss on a chassis dyno is SUPER EFFICIENT! Especially with an IRS car...an IRS suspension is not the the most efficient suspension when it comes to chassis dynos...If you are losing 9%, that’s VERY good!
I guess. It seems to be more the norm, from what I've seen. People get a RWHP number, then add a generous 15, 20%...whatever they want. That gets them an ego stroking "crank hp "number. If I did that, I could go around saying that my stock LT1 makes 320 hp. But it doesn't.
Mine put down 279 RWHP (and 312 tq). 330x0.93=279...a 7% loss from crank to wheel. Going the other way, 279x 1.08=301.3. An 8% gain, wheel to crank.
Buddies '88 5.0 with exhaust, timing and under drives did 238 RWHP. exhaust and under drives should have made that ~a 255hp engine. 255x0.93=237.1...so about a 7% loss from flywheel to crank. Going the other way, 238x1.08=257. About a 8% gain from wheel to crank.
Looking at my LS2, 400hp, C6, that did 366 to the wheel. 400x0.91=364; a 9% loss, crank to tire. Going the other way, 366x1.09=398.9; a little over a 9% gain, wheel to crank.
OTOH, my wife's CTS-V (400hp LS6 engine) did an embarrassin' 338 to the wheels, and that's about 15%. Why the diff in that car and the 400 horse LS2 in the 'Vette? Drivetrain weight. The Caddy has a staggering 50 lb flywheel, a retarded 50 lb driveshaft, big heavy hubs, big fatty 14" rotors and big heavy wheels. And there's your 15%. But most cars and certainly C4's, don't have dumb, heavy drivetrains like the V does. So for most cars, I think ~10% is more in line with reality.
OTOH, my wife's CTS-V (400hp LS6 engine) did an embarrassin' 338 to the wheels, and that's about 15%. Why the diff in that car and the 400 horse LS2 in the 'Vette? Drivetrain weight. The Caddy has a staggering 50 lb flywheel, a retarded 50 lb driveshaft, big heavy hubs, big fatty 14" rotors and big heavy wheels. And there's your 15%. But most cars and certainly C4's, don't have dumb, heavy drivetrains like the V does. So for most cars, I think ~10% is more in line with reality.
Interesting....I never engine dynoed my 355 after the build...just chassis dynoed it for tuning purposes after it was in the car, so I really have no real world numbers to see before and after to see what kind of power loss I have through the drive train. I wish I would have, but I had no access to an engine dyno at the time.
Interesting....I never engine dynoed my 355 after the build...just chassis dynoed it for tuning purposes after it was in the car, so I really have no real world numbers to see before and after to see what kind of power loss I have through the drive train. I wish I would have, but I had no access to an engine dyno at the time.
See dynos the same way. A # can be interesting but not an end all be all or basis to upgrade parts from.
the fact an LT1 cars losses are small yet another stick car can be 15%..seen some Turbo 400/high stall cars lose rediculous amounts to the tire but still run the number down the track, so imo #s dont mean much its how it gets laid down.
The comment about seeing 698 NA with ported heads, what application is this? That is a crap ton of power out of any smallblock
I guess. It seems to be more the norm, from what I've seen. People get a RWHP number, then add a generous 15, 20%...whatever they want. That gets them an ego stroking "crank hp "number. If I did that, I could go around saying that my stock LT1 makes 320 hp. But it doesn't.
Mine put down 279 RWHP (and 312 tq). 330x0.93=279...a 7% loss from crank to wheel. Going the other way, 279x 1.08=301.3. An 8% gain, wheel to crank.
Buddies '88 5.0 with exhaust, timing and under drives did 238 RWHP. exhaust and under drives should have made that ~a 255hp engine. 255x0.93=237.1...so about a 7% loss from flywheel to crank. Going the other way, 238x1.08=257. About a 8% gain from wheel to crank.
Looking at my LS2, 400hp, C6, that did 366 to the wheel. 400x0.91=364; a 9% loss, crank to tire. Going the other way, 366x1.09=398.9; a little over a 9% gain, wheel to crank.
OTOH, my wife's CTS-V (400hp LS6 engine) did an embarrassin' 338 to the wheels, and that's about 15%. Why the diff in that car and the 400 horse LS2 in the 'Vette? Drivetrain weight. The Caddy has a staggering 50 lb flywheel, a retarded 50 lb driveshaft, big heavy hubs, big fatty 14" rotors and big heavy wheels. And there's your 15%. But most cars and certainly C4's, don't have dumb, heavy drivetrains like the V does. So for most cars, I think ~10% is more in line with reality.
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The Ls2 vette engine is a 6.0L. The Ls6 is a 5.7L that be some difference
Last edited by Mike Holmen; 06-20-2018 at 08:05 PM.
I see most here may not be true gear heads.but I respect your input.I also know better to ever ask for it again
Do you want that 700 horsepower engine to last for repeated twenty minute road course sessions without blowing up, or will this 700 horsepower engine get a rest and a massage after every ten seconds of straightline exertion?
I would go with a big cubic engine. I love driving mine and Autocross it almost every weekend. Keep in mind this will take a lot of money. At this level you will break everything behind your motor if you have tires that can get traction.
If you would all go check the op's public profile, you would see he has not been active on the site (means logged in) since 6-6-18 at 6:43 pm which is the exact time he put up his last post saying most here are not true gearheads.
Either he was a troll or someone completely clueless about how much work and money it takes to make the C4 reliable at increased levels of performance and how compromises were made, such as putting a Dana 36 behind an auto trans instead of all C4's having the Dana 44. While it is a great machine, there were lots of compromises that we are working around.
Not to get into a p*ssing match with you but ...... also I see it was a little earlier than when the system logged him off and he told everyone kinda sorta to p.off
06-09-2018, 10:27 AM
