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Thread: Went to the dyno today

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Posts: 21-30 of 58
2009-05-13 19:38:02
#21
Originally Posted by Doctor
Also, with no intake vacuum, do you think there can be a problem with crank case pressure? Like I said my car blew the one small welsh plug out of the side of the head. And my breather pipe near the back of the VC, which has a small breather filter on also gets popped out!


Some thing is definately wrong, that is way too much blow by/crank case pressure. A lot of combustion pressures are getting pass the piston rings.

Do a leak down test before you make any changes.
2009-05-13 20:17:58
#22
You might want to look into a evac system, plumb the crank case/valve cover to a check valve hooked up to the header to suck the pressure out, that how we do it in all the car's in NY.
2009-05-14 07:15:15
#23
Originally Posted by 5speed
Some thing is definately wrong, that is way too much blow by/crank case pressure. A lot of combustion pressures are getting pass the piston rings.

Do a leak down test before you make any changes.


hmmm, not what I want to hear. But I'll look into that. The compression test I did was good. 210psi accross the board.


Originally Posted by kesi24
You might want to look into a evac system, plumb the crank case/valve cover to a check valve hooked up to the header to suck the pressure out, that how we do it in all the car's in NY.


That's what I've been thinking of doing also. Just need to source the parts to make that work. I have a spot just behind the header where the lambda sensor would normally go that I can make work for this.
2009-05-14 08:51:35
#24
Dyno sheet please!
2009-05-14 16:25:41
#25
Forgot to take it to work and scan it, but here is a pic of it I took with my phone.


Uncorrected figures at the hubs for 5707ft altitude. Add +/- 17% for sea level figures.
=

I realised today I have the girdle in there so first thing to do now is pull it out. That should get another few hp for free.



The motor:

2009-05-14 17:11:07
#26
Strange to see only 210psi with 16ve pistons.

Also when you say that the figures are at the hubs what do you mean? I think that dyno at Mrturbo is a twin-roller dyno.

Every dyno from FS4 I have seen keeps making power at 9000rpm. Yours stops early. Did you tried to alter the cam timing? How is your AFR?
2009-05-14 17:23:03
#27
Originally Posted by bill
Strange to see only 210psi with 16ve pistons.


What would you expect with 16ve pistons? Mine are shaved slightly, and have deeper valve reliefs cut in them, but since they are consistant accross the board I asume ring seal is healthy??
Also, cam timing would have an impact on the compression readings, so that could explain it.

Originally Posted by bill

Also when you say that the figures are at the hubs what do you mean? I think that dyno at Mrturbo is a twin-roller dyno.

I mean the figures are wheel hp. Yes the dyno is a twin roller. All our dyno's are like that.

Originally Posted by bill

Every dyno from FS4 I have seen keeps making power at 9000rpm. Yours stops early. Did you tried to alter the cam timing? How is your AFR?


I don't know what the AFR was. Will ask for it next time to be on the dyno sheet.

As for the powerband. It levels off at 7500 and stays like that to about 8000-8500rpm. The cams have been dialed by the engine builder. Going back to the dyno shorlty to play with the cam timing a bit.
2009-05-14 18:56:33
#28
Originally Posted by bill
Strange to see only 210psi with 16ve pistons.

Also when you say that the figures are at the hubs what do you mean? I think that dyno at Mrturbo is a twin-roller dyno.

Every dyno from FS4 I have seen keeps making power at 9000rpm. Yours stops early. Did you tried to alter the cam timing? How is your AFR?


The 210 psi is mostly from the FS4. The small cam has a lot of duration.For example when I had the FS4, I got 180-185 psi, once I swapped in the N1 intake cam it jump to 230-235 psi. But still I would expect DotorG to get at least 230 psi from his engine. The altitude might have something to do with it.

I also think it's odd for this engine to peak early with the FS4.

DoctorG, what is your total intake runner length, from the intake manifold flange to the end of the air horn?
2009-05-14 19:56:48
#29
Originally Posted by 5speed
The 210 psi is mostly from the FS4. The small cam has a lot of duration.For example when I had the FS4, I got 180-185 psi, once I swapped in the N1 intake cam it jump to 230-235 psi. But still I would expect DotorG to get at least 230 psi from his engine. The altitude might have something to do with it.

I also think it's odd for this engine to peak early with the FS4.

DoctorG, what is your total intake runner length, from the intake manifold flange to the end of the air horn?



Interesting. The guy who did my motor did mention even the low lobes had crazy duration, so it's possible yes. And he physically measured the actual degrees at which the valves start opening until they close, so I know his figures are correct. What compression did you run when you got those psi figures with the cams?

After I've played with the FS4 cam timing on the dyno I'll be throwing in derms' N1 cams for comparison. Will do another compression test then. How did your motor respond after switching from fs4's to n1's?

The runners from bellmouth to the head are aproximately 21cm or about 8 1/4 inches. It's shorter than usual, due to space constraints on the RHD model. Being that short it's great for high rpm power, but I think the cams are possibly messing things around a bit.
2009-05-14 20:36:40
#30
I'm not all that much of an itb fan either. I can vouch for the coast/upland dyno numbers differing down there in ZA. Also I can vouch for the fact that they swear by itbs.

I think the N1s will help too. FS4 is for the scrap bin.
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