Dyno run :(

[olgreydog7]

Not so good results. 388/347 was the best run. The motor dies in the upper rpm according to the dyno. On the street, she feels like she pulls all the way to 8000. She also feels alot stronger than just 40/40 more than the stock short block FR500 cam and intake build I did. The A/F stayed right at 12.5 until the very top where it dipped to 11.9. Something is not right. Basic specs are 322 ci big bore stroker, flat top pistons, 10.5:1, ported c heads, 235/239 cams, Sullivan intake, Hooker long tubes, o/r x, SLP LM2 catback, Al flywheel, Al driveshaft, 90 mm maf, 39lb injectors, twin GT pumps. Am I wrong, or should this have peaked much higher? Note the scales are different bewteen hp an torque.

 

[gmsux]

How did the dyno read the engines RPM? Did they tap into a COP or?

 

[clbailey]

Most dynos show rpm. Mine has an OBDII plug-in.

 

[Bmeagher]

Which tuning program are you using? SCT....FAST?

 

[fangs99]

There is a looped wire that sticks up on the COP wiring harness that is used for tach signal.... OP... Your hp curve does look really peaky and early... My stock 99 intake flattens the hp out at 6,100 but it holds it all the way 6,800 - 7,000rpm.

 

[olgreydog7]

There is a looped wire that sticks up on the COP wiring harness that is used for tach signal.... OP... Your hp curve does look really peaky and early... My stock 99 intake flattens the hp out at 6,100 but it holds it all the way 6,800 - 7,000rpm.

Yea, they had a clamp that went on a COP wire. They pulled the p-side coil cover to do it. Maybe a cylinder wasn't getting spark? That is exactly what bugs me, everything about this combo is set up to run in the higher rpm, and it didn't even run as high as a stock motor. Something is wrong for sure. It is tuned with an SCT Xcal2.

 

[99COBRA2881]

Stock power wire to the fuel pump(s)? You may need to use bigger gauge wire if you havent done so already.

 

[na svt]

388rw at 6500 is very good, but the power should continue to increase at the same rate until at least 7250 The last BB/stroker I did made peak at 7250 with a Sullivan and 234 deg intake cams installed at 111, it's power was similar to yours at 6100rpm.

IMO the problem is an airflow restriction, anywhere from the filter to the valves.

Stock power wire to the fuel pump(s)? You may need to use bigger gauge wire if you havent done so already.

Low voltage to the pump would present itself as a lean condition.

There is a looped wire that sticks up on the COP wiring harness that is used for tach signal.... OP... Your hp curve does look really peaky and early... My stock 99 intake flattens the hp out at 6,100 but it holds it all the way 6,800 - 7,000rpm.

N/A, stock intakes will peak at 6200-6300 and drop off soon after.

The curve has small spikes in it because the smoothing is set at "0"

 

[olgreydog7]

388rw at 6500 is very good, but the power should continue to increase at the same rate until at least 7250 The last BB/stroker I did made peak at 7250 with a Sullivan and 234 deg intake cams installed at 111, it's power was similar to yours at 6100rpm.

IMO the problem is an airflow restriction, anywhere from the filter to the valves.


Low voltage to the pump would present itself as a lean condition.



N/A, stock intakes will peak at 6200-6300 and drop off soon after.

This is what I am thinking. The valves, lash adjusters, followers, and springs are the FR500 stuff. I have a Specter filter on a JLT RAI right now IIRC. It should be clean, though I did not clean it recently. I have only put 3,000 miles on the car in the last 2 years. Could the cam timing be off? BTW, I do have the wiring upgrade for the fuel pumps. I wish the A/F didn't get cut off when he printed the dyno sheet. It did go rich in the upper RPM. Maybe the air flow dying off caused it? It was right at 12.5 the rest of the time.

 

[tmhutch]

Rather then shooting in the dark I'd be datalogging some WOT runs on the dyno and some on the street. Compare the two and see if their is anything obvious. If their isnt, I'd send the dyno datalogs to Don at LaSota Racing. For a very reasonable price he can analyze your information and spot whatever is going on with the combination.

 

[olgreydog7]

Already did. He actually sent me my money back because there was nothing he could see wrong. He agreed that this combo should peak higher though. You don't think it is possible that the tires were spinning on the dyno do you? There was a burnt rubber smell during the pulls. I'd be pretty pissed it that was the case. This dyno has had some big power cars on it, but mostly in the 4wd cars.

 

[na svt]

This is what I am thinking. The valves, lash adjusters, followers, and springs are the FR500 stuff. I have a Specter filter on a JLT RAI right now IIRC. It should be clean, though I did not clean it recently. I have only put 3,000 miles on the car in the last 2 years. Could the cam timing be off? BTW, I do have the wiring upgrade for the fuel pumps. I wish the A/F didn't get cut off when he printed the dyno sheet. It did go rich in the upper RPM. Maybe the air flow dying off caused it? It was right at 12.5 the rest of the time.

A compression check will show inconsistencies in the cam timing but for 235 def intake cams to peak so low they would have to be advanced an awful lot. Also, if the exhaust cams are set where John normally sets them the power shouldn't be dropping off so quick after peak.

I think you should ship it to Ohio for safe keeping while you're "at work"

 

[Don 95Vert]

Ya know, now that you mentioned that - I looked over the dyno graph again and it is really erratic - I originally assumed they had smoothing off. But since you mentioned the rubber smell, I'd bet the tires were spinning. When I see that happen on the dyno, it's usually a sign the the tires were spinning or the clutch was slipping. On an auto car it's a sign the engine blew past the converter clutch. I bet that is what happened (tire spin). You didn't log load and I'd have liked to have seen that, that might indicate it too (but maybe not). RPMs did get really high, really fast.

I'd vote for doing another run, make sure they strap it down really well, and if necessary, get a couple of large (obese) volunteers to sit in the truck during the run - we always seem to need to do that on really high HP cars. Also be sure the tires are inflated to like 28-32#.

I'd also ask them (if they did) to not use a tailpipe sniffer if they did.

Don LaSota

 

[gmsux]

The rpm pickup is fine so the scale is correct. Providing the engine is healthy and the tune is good which both sound like they are, then I would also suspect something with the dyno run. In the past I had a foxbody with big N/A hp (620rwhp) that dyno'd under expectations and peaked early. I switched dyno's and got some good numbers. Since you're in HI, you'll just have to try again. Be sure to do a thorough datalog with livelink.

 

[tmhutch]

I've never experienced the smell of burning rubber on the dyno without the tires breaking loose so I would agree with Don and others. The dyno sheet shows a loss of 80 ft lb of torque by 7500 RPM yet it pulls hard to 8000 when you're driving it. You would definately feel 80 - 100 ft lb of torque loss on the street so I too am thinking another run at the dyno might be worth it.

 

[olgreydog7]

A compression check will show inconsistencies in the cam timing but for 235 def intake cams to peak so low they would have to be advanced an awful lot. Also, if the exhaust cams are set where John normally sets them the power shouldn't be dropping off so quick after peak.

I think you should ship it to Ohio for safe keeping while you're "at work"

I'd think about it if I knew if I wasn't staying here.

Ya know, now that you mentioned that - I looked over the dyno graph again and it is really erratic - I originally assumed they had smoothing off. But since you mentioned the rubber smell, I'd bet the tires were spinning. When I see that happen on the dyno, it's usually a sign the the tires were spinning or the clutch was slipping. On an auto car it's a sign the engine blew past the converter clutch. I bet that is what happened (tire spin). You didn't log load and I'd have liked to have seen that, that might indicate it too (but maybe not). RPMs did get really high, really fast.

I'd vote for doing another run, make sure they strap it down really well, and if necessary, get a couple of large (obese) volunteers to sit in the truck during the run - we always seem to need to do that on really high HP cars. Also be sure the tires are inflated to like 28-32#.

I'd also ask them (if they did) to not use a tailpipe sniffer if they did.

Don LaSota

They did put a tailpipe sniffer in, but the exhaust blew it out of the pipe! I can't get my Zeitronix datalogger to talk to my laptop. I kept an eye on the gauge throughout the run though.

The rpm pickup is fine so the scale is correct. Providing the engine is healthy and the tune is good which both sound like they are, then I would also suspect something with the dyno run. In the past I had a foxbody with big N/A hp (620rwhp) that dyno'd under expectations and peaked early. I switched dyno's and got some good numbers. Since you're in HI, you'll just have to try again. Be sure to do a thorough datalog with livelink.

There is another Dynojet on island, but he is hard to get time with, all the Mustang guys use him though. The one I used is the only 4 wheel dyno around, so all the Evo and Sti guys go there. This was the only thing the holds me up about wheel spin. There are a couple of 600+ AWHP Evos and a GTR that used that dyno. Plus, I saw some high 400 RWHP Vettes on there too. Maybe I can ask them about wheel spin and see if they will give me a free pull or at least a discount.

I've never experienced the smell of burning rubber on the dyno without the tires breaking loose so I would agree with Don and others. The dyno sheet shows a loss of 80 ft lb of torque by 7500 RPM yet it pulls hard to 8000 when you're driving it. You would definately feel 80 - 100 ft lb of torque loss on the street so I too am thinking another run at the dyno might be worth it.

I try to not trust the butt dyno too much, but by 7000+, I'm holding on for dear life. Right now I have the rev limiter at 7800, and that comes really quick. I have a hard time not hitting when beat on her.

 

[olgreydog7]

Oh, btw my tires are about 5 years old. They have plenty of tread, only about 6,000 miles on them. They may not be the stickiest around anymore.

 

[tmhutch]

Don makes a good point, there is some very erratic action on that curve. I compared several different dynos on different combinations from mild to wild while changing the smoothing from 5 to 0 and none of them get near as crazy as your dyno sheet. Especially in the lower RPM where it is making those huge spikes up and down. That's not right.

 

[Bmeagher]

I had the same erratic curve on my dyno, i found i had coils breaking down. I installed gt500 coils, smoothed it right out.

 

[olgreydog7]

I had the same erratic curve on my dyno, i found i had coils breaking down. I installed gt500 coils, smoothed it right out.

I have been wondering about this too. How did you test the coils? Are the GT500 coils plug and play?