How much will short shifting effect an E.T.?
Thread Starter
Race Director
Joined: May 2001
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How much will short shifting effect an E.T.?
Ok I know it's a little bit vague because it really depends on your engine's power band, but here goes.
A friend of mine has a 87 Iroc with a freshly rebuilt L98 short block. On top of that he's got Trick Flow Kenny Duttweiler 62cc 23 degree heads, a Holley Street Dominator dual plane intake topped off with a Holley 600CFM 4150 style mechanical secondary double pumper carb. The valves are being controlled with an LT4 Hot Cam.
We put hardened pushrods in it the other day and re-adjusted the rockers. It's running great, the problem is that the owner still isn't comfortable with taking it over 5000 RPM's. I know the Hot Cam very well and I know it's gonna pull all the way to 6500 easily. He wants to take the car out to the track for some "easy" passes.
My question is, just how badly will short shifting an engine by at least 1500 RPM's affect E.T.? It's not set up real good anyway because the trans is only a T-5 from a V6 with a 3.97 first gear. Couple that with a 3.73 rear and you've got nothing in terms of speed.
My biggest fear is this. My friend very reluctantly used the LT4 Hot Cam. He hangs out a lot on the Camaro forums and just really wanted to go with a much bigger cam. I knew how he wanted to run the motor and told him that the Hot Cam would do well for daily driving. I'm afraid that he's gonna go out there, short shift it by 1500 RPM's and be upset about his lowsy E.T. Then he's gonna think he needs a bigger cam, which will make even less power and he'll be short shifting it by even more and be even slower.
It's an odd situation really with this guy. He wants a 12 second car but is reluctant to listen to the advice of his friends who have actually done it. He'll listen to anything that he reads off of 3rd Gen.org though. Then he has a solid motor that he doesn't want to push anywhere near it's limits, etc. It really is enough to make you want to scream!
So really, say you have my car. It's an LT with long tubes, LT4 hot cam, etc. It'll run a high 12.9 with a 2.2x 60' time without even trying really, you just have to shift it at 6500 RPM's What would it do if you shorted it by 1500 RPMs?!?! I say it'd be lucky to run a 13.50. What do you think?
A friend of mine has a 87 Iroc with a freshly rebuilt L98 short block. On top of that he's got Trick Flow Kenny Duttweiler 62cc 23 degree heads, a Holley Street Dominator dual plane intake topped off with a Holley 600CFM 4150 style mechanical secondary double pumper carb. The valves are being controlled with an LT4 Hot Cam.
We put hardened pushrods in it the other day and re-adjusted the rockers. It's running great, the problem is that the owner still isn't comfortable with taking it over 5000 RPM's. I know the Hot Cam very well and I know it's gonna pull all the way to 6500 easily. He wants to take the car out to the track for some "easy" passes.
My question is, just how badly will short shifting an engine by at least 1500 RPM's affect E.T.? It's not set up real good anyway because the trans is only a T-5 from a V6 with a 3.97 first gear. Couple that with a 3.73 rear and you've got nothing in terms of speed.
My biggest fear is this. My friend very reluctantly used the LT4 Hot Cam. He hangs out a lot on the Camaro forums and just really wanted to go with a much bigger cam. I knew how he wanted to run the motor and told him that the Hot Cam would do well for daily driving. I'm afraid that he's gonna go out there, short shift it by 1500 RPM's and be upset about his lowsy E.T. Then he's gonna think he needs a bigger cam, which will make even less power and he'll be short shifting it by even more and be even slower.
It's an odd situation really with this guy. He wants a 12 second car but is reluctant to listen to the advice of his friends who have actually done it. He'll listen to anything that he reads off of 3rd Gen.org though. Then he has a solid motor that he doesn't want to push anywhere near it's limits, etc. It really is enough to make you want to scream!
So really, say you have my car. It's an LT with long tubes, LT4 hot cam, etc. It'll run a high 12.9 with a 2.2x 60' time without even trying really, you just have to shift it at 6500 RPM's What would it do if you shorted it by 1500 RPMs?!?! I say it'd be lucky to run a 13.50. What do you think?
Le Mans Master
Joined: Nov 2003
Posts: 8,308
Likes: 157
From: NJ
Originally Posted by Nathan Plemons
Ok I know it's a little bit vague because it really depends on your engine's power band, but here goes.
A friend of mine has a 87 Iroc with a freshly rebuilt L98 short block. On top of that he's got Trick Flow Kenny Duttweiler 62cc 23 degree heads, a Holley Street Dominator dual plane intake topped off with a Holley 600CFM 4150 style mechanical secondary double pumper carb. The valves are being controlled with an LT4 Hot Cam.
We put hardened pushrods in it the other day and re-adjusted the rockers. It's running great, the problem is that the owner still isn't comfortable with taking it over 5000 RPM's. I know the Hot Cam very well and I know it's gonna pull all the way to 6500 easily. He wants to take the car out to the track for some "easy" passes.
My question is, just how badly will short shifting an engine by at least 1500 RPM's affect E.T.? It's not set up real good anyway because the trans is only a T-5 from a V6 with a 3.97 first gear. Couple that with a 3.73 rear and you've got nothing in terms of speed.
My biggest fear is this. My friend very reluctantly used the LT4 Hot Cam. He hangs out a lot on the Camaro forums and just really wanted to go with a much bigger cam. I knew how he wanted to run the motor and told him that the Hot Cam would do well for daily driving. I'm afraid that he's gonna go out there, short shift it by 1500 RPM's and be upset about his lowsy E.T. Then he's gonna think he needs a bigger cam, which will make even less power and he'll be short shifting it by even more and be even slower.
It's an odd situation really with this guy. He wants a 12 second car but is reluctant to listen to the advice of his friends who have actually done it. He'll listen to anything that he reads off of 3rd Gen.org though. Then he has a solid motor that he doesn't want to push anywhere near it's limits, etc. It really is enough to make you want to scream!
So really, say you have my car. It's an LT with long tubes, LT4 hot cam, etc. It'll run a high 12.9 with a 2.2x 60' time without even trying really, you just have to shift it at 6500 RPM's What would it do if you shorted it by 1500 RPMs?!?! I say it'd be lucky to run a 13.50. What do you think?
A friend of mine has a 87 Iroc with a freshly rebuilt L98 short block. On top of that he's got Trick Flow Kenny Duttweiler 62cc 23 degree heads, a Holley Street Dominator dual plane intake topped off with a Holley 600CFM 4150 style mechanical secondary double pumper carb. The valves are being controlled with an LT4 Hot Cam.
We put hardened pushrods in it the other day and re-adjusted the rockers. It's running great, the problem is that the owner still isn't comfortable with taking it over 5000 RPM's. I know the Hot Cam very well and I know it's gonna pull all the way to 6500 easily. He wants to take the car out to the track for some "easy" passes.
My question is, just how badly will short shifting an engine by at least 1500 RPM's affect E.T.? It's not set up real good anyway because the trans is only a T-5 from a V6 with a 3.97 first gear. Couple that with a 3.73 rear and you've got nothing in terms of speed.
My biggest fear is this. My friend very reluctantly used the LT4 Hot Cam. He hangs out a lot on the Camaro forums and just really wanted to go with a much bigger cam. I knew how he wanted to run the motor and told him that the Hot Cam would do well for daily driving. I'm afraid that he's gonna go out there, short shift it by 1500 RPM's and be upset about his lowsy E.T. Then he's gonna think he needs a bigger cam, which will make even less power and he'll be short shifting it by even more and be even slower.
It's an odd situation really with this guy. He wants a 12 second car but is reluctant to listen to the advice of his friends who have actually done it. He'll listen to anything that he reads off of 3rd Gen.org though. Then he has a solid motor that he doesn't want to push anywhere near it's limits, etc. It really is enough to make you want to scream!
So really, say you have my car. It's an LT with long tubes, LT4 hot cam, etc. It'll run a high 12.9 with a 2.2x 60' time without even trying really, you just have to shift it at 6500 RPM's What would it do if you shorted it by 1500 RPMs?!?! I say it'd be lucky to run a 13.50. What do you think?
Le Mans Master
Joined: Feb 1999
Posts: 6,172
Likes: 11
From: somers, ny
With my SR 350 i changed my shift light from 6000 to 5000 one day trying not to get thrown out for no roll bar and it made almost no difference...maybe a couple hundredths and a stiff repremand in the tower. i suppose a combo that's more suited to high revs would certainly make more of a difference.
Thread Starter
Race Director
Joined: May 2001
Posts: 14,165
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Yeah the SR probably starts to run out of breath above 5000. Not that it doesn't still pull, but rather you make about the same effective power if you go ahead and shift. It's all about area under the curve. The SR is suited to more low end grunt.
I'm thinking about taking my car out there and setting the rev limiter to 5000, the shift light to 4700 and seeing what happens. Nothing impresseive I'm sure
I'm thinking about taking my car out there and setting the rev limiter to 5000, the shift light to 4700 and seeing what happens. Nothing impresseive I'm sure
Former Vendor
Joined: Jun 2001
Posts: 7,204
Likes: 6
From: St Marys PA
Nathan,
Why are you worried about it? Tell the guy what he has to do and if he doesn't listen, runs a poor ET and decides to put a larger cam in it, and runs even slower the next time out - He can learn the hard way.
People are sometimes hard headed - either you have to "show" them or they have to learn on their own.
All you can do is offer to help.
Why are you worried about it? Tell the guy what he has to do and if he doesn't listen, runs a poor ET and decides to put a larger cam in it, and runs even slower the next time out - He can learn the hard way.
People are sometimes hard headed - either you have to "show" them or they have to learn on their own.
All you can do is offer to help.
Race Director
Joined: Oct 1999
Posts: 13,298
Likes: 14
From: Somers NY
Originally Posted by ski_dwn_it
Nathan,
Why are you worried about it? Tell the guy what he has to do and if he doesn't listen, runs a poor ET and decides to put a larger cam in it, and runs even slower the next time out - He can learn the hard way.
People are sometimes hard headed - either you have to "show" them or they have to learn on their own.
All you can do is offer to help.
Why are you worried about it? Tell the guy what he has to do and if he doesn't listen, runs a poor ET and decides to put a larger cam in it, and runs even slower the next time out - He can learn the hard way.
People are sometimes hard headed - either you have to "show" them or they have to learn on their own.
All you can do is offer to help.
Same deal here... you can tell him what to do.. but ya Can't Make Him Do It
I'd tell him to put in a Comp elim motor (de-stroked small block) ya know a 10,500 rpm job.. & say ok you can shift at 7,000.. & when he shifts at 5000 & runs 14.05 he'll get the idea
Safety Car
Joined: Apr 2004
Posts: 4,532
Likes: 7
From: Lahaina Hi
I would not worry about it .The car with that set up will launch hard
and he will have to short shift to keep up with the car .
I think he will not have any problem turning 12's with that set up.
and he will have to short shift to keep up with the car .
I think he will not have any problem turning 12's with that set up.
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Thread Starter
Race Director
Joined: May 2001
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Likes: 9
Originally Posted by ski_dwn_it
Nathan,
Why are you worried about it? Tell the guy what he has to do and if he doesn't listen, runs a poor ET and decides to put a larger cam in it, and runs even slower the next time out - He can learn the hard way.
People are sometimes hard headed - either you have to "show" them or they have to learn on their own.
All you can do is offer to help.
Why are you worried about it? Tell the guy what he has to do and if he doesn't listen, runs a poor ET and decides to put a larger cam in it, and runs even slower the next time out - He can learn the hard way.
People are sometimes hard headed - either you have to "show" them or they have to learn on their own.
All you can do is offer to help.
Thread Starter
Race Director
Joined: May 2001
Posts: 14,165
Likes: 9
Originally Posted by REDC4CORVETTE
I would not worry about it .The car with that set up will launch hard
and he will have to short shift to keep up with the car .
I think he will not have any problem turning 12's with that set up.
and he will have to short shift to keep up with the car .
I think he will not have any problem turning 12's with that set up.
He claims he knows that it'll run for crap shifting it like that, he just wants to see what it'll do. My question is WHY? If you're not gonna go to the track to run it for everything it's got, why go to the track?
Former Vendor
Joined: Jun 2001
Posts: 7,204
Likes: 6
From: St Marys PA
Originally Posted by Nathan Plemons
First gear is the real bastard to this car. I imagine he would have to short shift it, or just launch in second gear. For alll the rest of the gears though he's gonna need as much as he can get out of that motor and 5000 RPM's just doesn't do it.
He claims he knows that it'll run for crap shifting it like that, he just wants to see what it'll do. My question is WHY? If you're not gonna go to the track to run it for everything it's got, why go to the track?
He claims he knows that it'll run for crap shifting it like that, he just wants to see what it'll do. My question is WHY? If you're not gonna go to the track to run it for everything it's got, why go to the track?
Nathan.
By the sound of it, your friend is not a real avid track racer. Therefore I will bet dime to dollar if he says he is going to shift at 5000 RPM, even if the shift light is set at 5k, he will probably get his shifts off at about 5900-6200 RPM.
Nailing a perfect RPM is not an easy thing to do, and is nearly impossible for a person without a lot of track time.
A selected RPM come on VERY quick, add adrenaline and you get unaccurate shifting.Lastly if he is going by the stock tach, I can almost assure you he will be off my 1000 RPM to the high, cause of the tach lag and also its inaccuracy. Most likely he will not even be looking at the tach on the shift and be going by ear, which could land him anywhere.
If he wants to start out low and work his way up, given he is accurate - he will find where he needs to shift. As mentioned - of you tell him 6500 and he shoots for that first time out, he will probably be in the 7k+ range which is WAY WAY too high.
Let the man sort it out on his own. If you want to give him something to strive for, get in the car and make a pass - set the ET goal and hand him back the keys. Then he knows the car can do it, and its just him and your off the hook.
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Race Director
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Heh, I don't want to drive his car at the track. He's got some crap that I hang my foot on trying to get off the clutch. Until he fixes that I don't need to even try or I'd just roast the clutch off.
Thread Starter
Race Director
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Well he did take his car out to the track and as expected he's not happy. He ran twice, getting a 14.8 and a 14.3 both at 100 MPH. He managed a 2.1 60' which isn't all that terrible considering his first time out in this car and all. Hell I usually spin my way to a 2.2x
Apparently he decided to split the difference on the shifting, he thinks he was shifting at 5700.
Here's the problem though with that setup, the gear ratios in the trans are as follows:
3.97
2.34
1.46
1.00
0.79
Doing the math, if he really did shift at 5700 RPM's coming out of first gear he would land at 3300 RPM's which is just way too low for this engine. Going into third he'd land at 3600 which is a little better but still not a lot.
Hell a V-8 T-5 would get him to 3800 RPM's coming out of first which is a lot better. He has some tuning issues to deal with for sure but the trans certainly isn't helping him any. He needs something with some closer spaced gears so he can stay in his power band. Of course shifting at a higher RPM will put him further up there but it's still gonna be far from optimal. A T-56 would do wonders for him.
Apparently he decided to split the difference on the shifting, he thinks he was shifting at 5700.
Here's the problem though with that setup, the gear ratios in the trans are as follows:
3.97
2.34
1.46
1.00
0.79
Doing the math, if he really did shift at 5700 RPM's coming out of first gear he would land at 3300 RPM's which is just way too low for this engine. Going into third he'd land at 3600 which is a little better but still not a lot.
Hell a V-8 T-5 would get him to 3800 RPM's coming out of first which is a lot better. He has some tuning issues to deal with for sure but the trans certainly isn't helping him any. He needs something with some closer spaced gears so he can stay in his power band. Of course shifting at a higher RPM will put him further up there but it's still gonna be far from optimal. A T-56 would do wonders for him.
Safety Car
Joined: Sep 2000
Posts: 3,524
Likes: 4
From: Hinckley Ohio
Originally Posted by Nathan Plemons
Well he did take his car out to the track and as expected he's not happy. He ran twice, getting a 14.8 and a 14.3 both at 100 MPH. He managed a 2.1 60' which isn't all that terrible considering his first time out in this car and all. .
Sounds like he drives like me....14.8 vs 14.3 at the same speed.......
Anyhow last time out I did one run with a 2.39 60ft......the car then totally lost traction and I let off......thought about it for 1-2 seconds....put it in 4th and nailed it......14.722@103.47mph.........
The ultimate short shift...1st to 4th
Best part of the story........ricer in the other lane ran a 14.794...... I won!!! Actually by 0.2019sec due to my better(?) reaction time
Melting Slicks
Joined: May 2001
Posts: 3,270
Likes: 26
From: Winchester VA
Cruise-In V Veteran
Originally Posted by Nathan Plemons
Well he did take his car out to the track and as expected he's not happy. He ran twice, getting a 14.8 and a 14.3 both at 100 MPH. He managed a 2.1 60' which isn't all that terrible considering his first time out in this car and all. Hell I usually spin my way to a 2.2x
Apparently he decided to split the difference on the shifting, he thinks he was shifting at 5700.
Here's the problem though with that setup, the gear ratios in the trans are as follows:
3.97
2.34
1.46
1.00
0.79
Doing the math, if he really did shift at 5700 RPM's coming out of first gear he would land at 3300 RPM's which is just way too low for this engine. Going into third he'd land at 3600 which is a little better but still not a lot.
Hell a V-8 T-5 would get him to 3800 RPM's coming out of first which is a lot better. He has some tuning issues to deal with for sure but the trans certainly isn't helping him any. He needs something with some closer spaced gears so he can stay in his power band. Of course shifting at a higher RPM will put him further up there but it's still gonna be far from optimal. A T-56 would do wonders for him.
Apparently he decided to split the difference on the shifting, he thinks he was shifting at 5700.
Here's the problem though with that setup, the gear ratios in the trans are as follows:
3.97
2.34
1.46
1.00
0.79
Doing the math, if he really did shift at 5700 RPM's coming out of first gear he would land at 3300 RPM's which is just way too low for this engine. Going into third he'd land at 3600 which is a little better but still not a lot.
Hell a V-8 T-5 would get him to 3800 RPM's coming out of first which is a lot better. He has some tuning issues to deal with for sure but the trans certainly isn't helping him any. He needs something with some closer spaced gears so he can stay in his power band. Of course shifting at a higher RPM will put him further up there but it's still gonna be far from optimal. A T-56 would do wonders for him.
I have a 3.27 first 2.13 second and 3.73 rear. Going from 3.07 to 3.73 I lost about 4MPH and ~.6 of a second. His gear situation is worse and behind a less powerful motor. As you said, he is losing alot of time just in gearing. He should almost be happy at 14.3 given the current setup with the number of things working against him.
My 3.07's arrived today....
Team Owner
Joined: Oct 2004
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From: altered state
St. Jude Donor '05
Let the man sort it out on his own. If you want to give him something to strive for, get in the car and make a pass - set the ET goal and hand him back the keys. Then he knows the car can do it, and its just him and your off the hook.
Beat me to it...Hope your friend gets things sorted out..Sure bugs me when someone wont use the potential of their motor or wont run it!
I put together a motor for a friend about a year ago, will run at 7000 rpm all day! He's too afraid to go to the track
, he'd rather lope it through cruise ins playing Mr. cool fouling the plugs and washing the cylinders down..What a waste!
Beat me to it...Hope your friend gets things sorted out..Sure bugs me when someone wont use the potential of their motor or wont run it!
I put together a motor for a friend about a year ago, will run at 7000 rpm all day! He's too afraid to go to the track
, he'd rather lope it through cruise ins playing Mr. cool fouling the plugs and washing the cylinders down..What a waste!
Thread Starter
Race Director
Joined: May 2001
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Well it turns out he found a problem with his distributor which was allowing him 0 timing advance. Kinda exaplains those wierd driveability problems and could certainly account for some lost HP. We were gonna go back out to the track this weekend but some bracket racing tourny has the track tied up ALL weekend.
They would wait until spring break to do that.
They would wait until spring break to do that.
