strange t-rex numbers
09-28-2007, 10:10 AM
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strange t-rex numbers Maybe some of you have seen numbers like this before, but it's not what I was expecting.
I have an ls6 block ( stock ) 241 heads ( stock ) ls1 intake, T-rex, 1 7/8ths longtubes, m6 all in a 90 rx7 with a 4.11 rear. Been driving around on the stock tune for the last two weeks or so and finally made it to the dyno last night. It was a mustang dyno and the numbers we got look like this.
419 ft lbs @ 4195 rpm and 378 hp @ 5206 rpm.
And the thing was falling like a rock just after 5200.
Now I have never seen a 346 with this much cam make more tq than hp, and I really would not have anticpated breaking 400 rwtq at all, more likley 370ish and 420ish hp with my setup and I have the exact opposite.
Let me also say that I left the dyno angry with the shop owner as he basically told myself and the tuner that we were done and that the car would not make anymore power. I used to tune for a living, not ls1's but tuning either way. I think the car needs more timing up top and still needs some work on the af, but with his attitude I decided to leave, call it a night and just go to another dyno where we will be left alone... even if we blow it up, it's our choice. So I will be back on a dyno soon and likley a dynojet this time. But in the meantime, any ideas or insight?
I have an ls6 block ( stock ) 241 heads ( stock ) ls1 intake, T-rex, 1 7/8ths longtubes, m6 all in a 90 rx7 with a 4.11 rear. Been driving around on the stock tune for the last two weeks or so and finally made it to the dyno last night. It was a mustang dyno and the numbers we got look like this.
419 ft lbs @ 4195 rpm and 378 hp @ 5206 rpm.
And the thing was falling like a rock just after 5200.
Now I have never seen a 346 with this much cam make more tq than hp, and I really would not have anticpated breaking 400 rwtq at all, more likley 370ish and 420ish hp with my setup and I have the exact opposite.
Let me also say that I left the dyno angry with the shop owner as he basically told myself and the tuner that we were done and that the car would not make anymore power. I used to tune for a living, not ls1's but tuning either way. I think the car needs more timing up top and still needs some work on the af, but with his attitude I decided to leave, call it a night and just go to another dyno where we will be left alone... even if we blow it up, it's our choice. So I will be back on a dyno soon and likley a dynojet this time. But in the meantime, any ideas or insight?
09-28-2007, 12:22 PM
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Staging Lane
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Should have mentioned that I am running patriot dual springs. Didn't seem to be valve float as the graph was smooth. Af's were in line too. I have 28.8's in it and a 255 walbro in the tank and a new filter... I just don't understand the tq number at all, seems way to high even if everything else was where I expected it.
09-28-2007, 12:34 PM
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What kind of dyno? Its not accurate. a cam only motor with a ls1 intake does not make 419 lbft. It would be pretty standard if you revered the numbers.
09-28-2007, 01:09 PM
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It was done on a mustang dyno stripstar. And I agree about the numbers seeming to be reversed, although it still doesn't explain the rpm range it made it's respective peaks at.
Hennytime- no doubt that it is choking it a bit, but it still shouldn't behave like this I wouldn't think.
JamesSS- If I could afford one you can bet that it would already be on there
We're going to use a buddy's dynojet next week and continue on it and see what happens there. I do have the graph but no way to scan it here at work.I'll scan an post later if I can when I get home. It looks like a a small cammed 400+ ci motor when you look at the graph. Or something you'd build for a truck to tow with, I mean it makes 320+ ft lbs by 2200 rpm! Not normal for this cam.
Hennytime- no doubt that it is choking it a bit, but it still shouldn't behave like this I wouldn't think.
JamesSS- If I could afford one you can bet that it would already be on there
We're going to use a buddy's dynojet next week and continue on it and see what happens there. I do have the graph but no way to scan it here at work.I'll scan an post later if I can when I get home. It looks like a a small cammed 400+ ci motor when you look at the graph. Or something you'd build for a truck to tow with, I mean it makes 320+ ft lbs by 2200 rpm! Not normal for this cam. Trending Topics
09-28-2007, 01:43 PM
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Originally Posted by angelR
It was done on a mustang dyno stripstar. And I agree about the numbers seeming to be reversed, although it still doesn't explain the rpm range it made it's respective peaks at.
Hennytime- no doubt that it is choking it a bit, but it still shouldn't behave like this I wouldn't think.
JamesSS- If I could afford one you can bet that it would already be on there We're going to use a buddy's dynojet next week and continue on it and see what happens there. I do have the graph but no way to scan it here at work.I'll scan an post later if I can when I get home. It looks like a a small cammed 400+ ci motor when you look at the graph. Or something you'd build for a truck to tow with, I mean it makes 320+ ft lbs by 2200 rpm! Not normal for this cam.
Hennytime- no doubt that it is choking it a bit, but it still shouldn't behave like this I wouldn't think.
JamesSS- If I could afford one you can bet that it would already be on there
We're going to use a buddy's dynojet next week and continue on it and see what happens there. I do have the graph but no way to scan it here at work.I'll scan an post later if I can when I get home. It looks like a a small cammed 400+ ci motor when you look at the graph. Or something you'd build for a truck to tow with, I mean it makes 320+ ft lbs by 2200 rpm! Not normal for this cam.
09-28-2007, 09:30 PM
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They do intersect at 5252. But I am thinking more and more that it was an rpm issue. Take the 370ish tq I have at "5200 rpm" and pretend for a sec that it actually had that figure at 6200 rpm and you get 444 hp, surely optimistic, but food for thought and much closer to the expected relationship.
09-29-2007, 01:44 AM
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cam looks like its off a tooth number one, number two the dyno is not configured right, no way its gonna put down 400 TQ, it should be more like 300 with that situation. Check your cam timing, and see if its lined up dot to dot.
09-29-2007, 06:34 PM
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Do you have a graph of the motor running past 5200rpm. If it is falling off I agree with the cam check. If the graph is virtually straight and level after 5200rpm I would suggest you are running out of air for whatever reason.
10-01-2007, 11:00 AM
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I want to whatch this one and see what happens. I am thinking cam timing too. How does it feel on the street? You would notice that much torque on the street. What car was the callibration set-up for? Do you have the curves of the dyno resistance? Or at least numbers?