Pathetic 427 numbers...help!
09-19-2007, 10:03 PM
#41
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Originally Posted by WMSuperSport
Please do yourself a favor and temperature check the exhaust primaries with a temp gun. But I know you're low on time. To me it would be worth the cost to have the only badass ls1 in japan, but im hardcore like that. good luck and thanks for serving the country. we really appreciate you and what you do.
Wes
Wes
Yes, good luck and god bless! Thanks for serving!!
09-20-2007, 01:35 AM
#43
FormerVendor
Power is not falling off like if it had valve float but the power is just low. I also would say it is down a cylinder at WOT which is what I told him as well. I know Ryan has hardly any time left but there is something simple going on. I can't count the number of cars that picked up 50-100 hp when I was back inside HPE that had things that were killing a cylinder (or several times 2) under WOT that didn't show up at normal rpm especially bad wires or cracked plugs. An almost identical sister engine to this one made 590 RWHP SAE with only 22 degrees of timing and a lil rich setup for a medium amount of NOS through a 6-spd drivetrain with normal peripherals and the bigger Kooks headers. There's no way it would only be making 438 TQ as all the 346s we do make more than that. I think when Ryan finds it there will be a very simple problem.
09-25-2007, 09:14 PM
#47
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Originally Posted by brad8266
MAP @ idle is right. Thats too bad about the low numbers. I would have personally went with a different set of heads like AFR or TFS and also ran a FAST manifold. You could be losing power from the heads and intake, hard for me to say really though. Your TQ drops off right after 6K which is why the power does not increase after 6k, this is not supposed to happen when you have a cam that size, it shold keep making TQ a bit longer and increase power up high in the RPM's. I feel as though your motor is being choked by something, which I would guess is heads and intake. What did the heads flow? Its hard to believe that your 427 only makes 438 TQ and my little 347 makes 415 TQ. Something is holding it back.
If you have good consistent compression numbers than there is not really any need to do a leakdown test.
Hope you get it figures out man, that motor is a beast in that little car.
If you have good consistent compression numbers than there is not really any need to do a leakdown test.
Hope you get it figures out man, that motor is a beast in that little car.
09-25-2007, 09:20 PM
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Originally Posted by Blown2000SS
get rid of the stock coils and get a real spark/ignition system.
They make over 1000 rwhp no problem! Shouldn't be the issue, I run them.
09-25-2007, 09:56 PM
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Yeah keep us up to date I too was a little disappointed with my numbers outta my 427 but I figure mine is because of the alt im at 4500 ft and Im using the unported L92s and L76 intake
09-27-2007, 09:56 PM
#51
I had a similar problem. Car idled fine, went through all the diagnostic tests and same thing, nothing wrong, but a total dog driving the car.
Finally, pulled into the garage and it was now late and the lights were off and I got under the car while it was running and could actually see a flash of light coming from the driver's side. The #5 plug was cracked and I could see it arcing on the cylider head every time it fired.
So that's an easy way to visually check for cracked plugs, check the car when its dark out and see if you can see any sparks.
Finally, pulled into the garage and it was now late and the lights were off and I got under the car while it was running and could actually see a flash of light coming from the driver's side. The #5 plug was cracked and I could see it arcing on the cylider head every time it fired.
So that's an easy way to visually check for cracked plugs, check the car when its dark out and see if you can see any sparks.
09-28-2007, 06:53 AM
#52
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Originally Posted by The Alchemist
I had a similar problem. Car idled fine, went through all the diagnostic tests and same thing, nothing wrong, but a total dog driving the car.
Finally, pulled into the garage and it was now late and the lights were off and I got under the car while it was running and could actually see a flash of light coming from the driver's side. The #5 plug was cracked and I could see it arcing on the cylider head every time it fired.
So that's an easy way to visually check for cracked plugs, check the car when its dark out and see if you can see any sparks.
Finally, pulled into the garage and it was now late and the lights were off and I got under the car while it was running and could actually see a flash of light coming from the driver's side. The #5 plug was cracked and I could see it arcing on the cylider head every time it fired.
So that's an easy way to visually check for cracked plugs, check the car when its dark out and see if you can see any sparks.
Good suggestion. Bo's squirt bottle idea is good too. Lots of help on this site.
10-01-2007, 11:26 AM
#53
Not to hijack the thread or anything but this guy is kinda having the same problem im having. My car is down about 75rwhp and I did the temp gun on the primarys and they were like all 270 except 1 that was 650 degrees. Swapped injectors on it and chased wires any idea why it would run so hot guys? research the threads I made if anyone has any ideas i made but its got all my trouble shooting ive done in there.
10-29-2014, 01:37 AM
#54
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~Bump from the dead!~ =)
Well, I pulled the RX-7 out of storage and fired it back up. I recently put it back on the road and brought it up to FBC in Baltimore so Jason could tune it. Mustang Dyno, even worse results
430hp, 400 tq. I'll post the graph but it looks a lot like the first page still. Engine mods are unchanged other than a new air intake setup.
- Checked throttle body, opens 100%
- Leakdown all cylinders...4%-6%
- Cranking compression... 195 PSI warm
- Shot the primaries with a temp gun after it warmed up and saw ~270F a few inches from the head on all of them.
- New plugs, new gas.
All done before the dyno appt.
The car drives just fine, doesn't miss, choke or act strange at all.
I pulled the valve covers and started looking at lifter preload. On a cold engine, should I be able to spin any of the pushrods? All of mine (on the base circle) spin. I did loosen the rocker on number 1 intake. I get about 5/8 of a swing before my torque wrench clicks @ 22. It's hard to get a consistent reading on my dial indicator, but it appears to be ~.020" of lifter preload. I've read that a full swing is typically .047", so maybe my dial indicator is about right.... seems a bit on the low side for the recommended preload, Morel recommends ~.050". However, everything I've read thus far tells me that's probably not where my missing power is at. Pushrods are 7.675" in length.
Anybody want to take a crack at some virtual troubleshooting on LS1Tech's longest running problem? =)
Thanks,
Ryan
Well, I pulled the RX-7 out of storage and fired it back up. I recently put it back on the road and brought it up to FBC in Baltimore so Jason could tune it. Mustang Dyno, even worse results
430hp, 400 tq. I'll post the graph but it looks a lot like the first page still. Engine mods are unchanged other than a new air intake setup.
- Checked throttle body, opens 100%
- Leakdown all cylinders...4%-6%
- Cranking compression... 195 PSI warm
- Shot the primaries with a temp gun after it warmed up and saw ~270F a few inches from the head on all of them.
- New plugs, new gas.
All done before the dyno appt.
The car drives just fine, doesn't miss, choke or act strange at all.
I pulled the valve covers and started looking at lifter preload. On a cold engine, should I be able to spin any of the pushrods? All of mine (on the base circle) spin. I did loosen the rocker on number 1 intake. I get about 5/8 of a swing before my torque wrench clicks @ 22. It's hard to get a consistent reading on my dial indicator, but it appears to be ~.020" of lifter preload. I've read that a full swing is typically .047", so maybe my dial indicator is about right.... seems a bit on the low side for the recommended preload, Morel recommends ~.050". However, everything I've read thus far tells me that's probably not where my missing power is at. Pushrods are 7.675" in length.
Anybody want to take a crack at some virtual troubleshooting on LS1Tech's longest running problem? =)
Thanks,
Ryan
10-29-2014, 02:36 AM
#55
This may be the only valid bump from the dead ever on this site.....Are you over on norotors as well? Good core group of folks over there.
Sorry to hear about your 427 issues. My LS1 with 4.10's would spin 1,2 and 3 no prob unless they were really sticky tires. Hope you get it sorted out.
I would note that there can be a lot of power to be hard in .5 AFR. I gained 30 from 12.1 to 12.7.
I'd personally run a 7.700" rod but you are probably right, I doubt your power missing is there.
On a cold engine you should be able to spin the push rods but they should be a little tight. If you turns the motor over by hand they should be a bit more lose but will tighten back up a little.
Get that AFR a little tighter inline and take it to the track. Your MPH will tell the true story. What's your timing at from 3k to redline?
Sorry to hear about your 427 issues. My LS1 with 4.10's would spin 1,2 and 3 no prob unless they were really sticky tires. Hope you get it sorted out.
I would note that there can be a lot of power to be hard in .5 AFR. I gained 30 from 12.1 to 12.7.
I'd personally run a 7.700" rod but you are probably right, I doubt your power missing is there.
On a cold engine you should be able to spin the push rods but they should be a little tight. If you turns the motor over by hand they should be a bit more lose but will tighten back up a little.
Get that AFR a little tighter inline and take it to the track. Your MPH will tell the true story. What's your timing at from 3k to redline?
10-29-2014, 05:21 AM
#56
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This may be the only valid bump from the dead ever on this site.....Are you over on norotors as well? Good core group of folks over there.
Sorry to hear about your 427 issues. My LS1 with 4.10's would spin 1,2 and 3 no prob unless they were really sticky tires. Hope you get it sorted out.
I would note that there can be a lot of power to be hard in .5 AFR. I gained 30 from 12.1 to 12.7.
I'd personally run a 7.700" rod but you are probably right, I doubt your power missing is there.
On a cold engine you should be able to spin the push rods but they should be a little tight. If you turns the motor over by hand they should be a bit more lose but will tighten back up a little.
Get that AFR a little tighter inline and take it to the track. Your MPH will tell the true story. What's your timing at from 3k to redline?
Sorry to hear about your 427 issues. My LS1 with 4.10's would spin 1,2 and 3 no prob unless they were really sticky tires. Hope you get it sorted out.
I would note that there can be a lot of power to be hard in .5 AFR. I gained 30 from 12.1 to 12.7.
I'd personally run a 7.700" rod but you are probably right, I doubt your power missing is there.
On a cold engine you should be able to spin the push rods but they should be a little tight. If you turns the motor over by hand they should be a bit more lose but will tighten back up a little.
Get that AFR a little tighter inline and take it to the track. Your MPH will tell the true story. What's your timing at from 3k to redline?
It'll still blow blow the tires off in first and second without trying too hard. Of course, it would do that when I had the LS1 in it =). BTW, I'm running 3.55s in an 8.8 Cobra IRS now.
Ryan
10-29-2014, 12:50 PM
#58
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I think the Cobra diff was a good move but there is a lot more noise transmitted to the body with it. I'm using the OG "JimLab" cradle. I'm getting ready to jack it up and see how it's held up so far.
Ryan
Ryan
10-29-2014, 12:56 PM
#59
As stated I would lean it out some to around 12.8:1. I would also try a different dyno. As posted the curve and power peaks look where they should be, just lower than they should be.