Sometimes you just gotta start over....
- Thread starter JayC
- Start date
Correction
I had to dig up and check through my notes, and found that I was wrong on the rpm range. The BHP peaks and goes relatively flat from 7300 to 8200 rpm. Actually peaking at 8000. The big cubes knock it down a bit. I was right about the BHP figure.
I had to dig up and check through my notes, and found that I was wrong on the rpm range. The BHP peaks and goes relatively flat from 7300 to 8200 rpm. Actually peaking at 8000. The big cubes knock it down a bit. I was right about the BHP figure.
I'm finishing up a freshen up job on the engine today, as a matter of fact. The engine is still on the stand. I've taken quite a few pictures documenting the assembly. Some of you might now be able to make some sense of 'The Plumbing Nightmare' by following the pictures. When I'm done with the wrenches (trying to make a big race Friday night), I'll post the documentary up on a different thread and add a link to it here. I don't want to intrude more than I have already on this thread.
Well we tried to dyno it again today. When the rpms got to 7000 it would spin the tires. Kinda like tire shake. it rattled the switch panel loose from the harness. So now it is time to finalize all the loose ends and test it thursday. I was not ready for was the massive amounts of fuel consumption. Went through 7 gallons in 3 pulls. We are also trying to make a 1/4 mile run friday at VMP, if things go well at benson thursday.
I have tried to tune a few big tire cars on roller dynos and have had hte same thing happen.
EightSecV6
MDBL
- Joined
- Jul 18, 2001
The engine will absolutely make more power than needed to get the job done at 2100#!
i think it is a rear weight issue. we would have put jay on the back but no place to put him. funny thing is we built a small tire 28 x 10.5 and made 1401 rwhp and another board member north of 1600 rwhp, without the tire issue. The tune is pretty close so we can fine tune it at the track. The track seems to load it better. The way this thing accelerates, it should be quick.
I know it might sound whacky...but how about tieing down the rear so it will not hop...or throwing some weight back there.....the rollers do not have the traction that a track would...plus down force on rear spoiler etc....just a thought...to simulate...real world....
six shooter
Quiet Member
- Joined
- May 26, 2001
Do you guys have a smaller set of rear tires to track test with ? ( just in case you see tire shake while working on the tune )
7 gallons in 3. That is making some power.
- Joined
- May 27, 2001
One thing we're finding now is that alcohol seems to need more timing than gasoline. 26 degrees seems to be the threshold. Anything less and you start to see the power dropping. 21 degrees and the engine is an absolute dog. Beings that we're in new territory here, I'm not sure what the safe limit is considering it's looking like we're going to need to run 35-40 PSI on top of the 11:1 compression ratio we're starting with to get in the horsepower range we want to be in.
This was kind of a surprise. I wasn't expecting to need to run that kind of boost on this engine but it seems to like it and we're keeping the EGTs way down to keep things safe. We've only cracked 1000 degrees on any of the cylinders once.
BTW, Don.. a page or so back we talked about EGTs and their accuracy vs update time. I talked to the manufacturer of the engine management system who told me it's instantaneous and that the EGTs are monitored only after firing the cylinder.
This system really is on a whole nother level than anything else I've ever worked with including Motec and Autronics. It's strictly a race only setup tho. The data logging capabilities of this unit are phenomenal.. you can really get yourself into data overload quickly with this system. The amount of trims and adjustments in this system are insane. You have gear specific timing tables, gear specific fuel trims, RPM based individual cylinder correction, altitude correction, etc. It's a pretty awesome system.
This was kind of a surprise. I wasn't expecting to need to run that kind of boost on this engine but it seems to like it and we're keeping the EGTs way down to keep things safe. We've only cracked 1000 degrees on any of the cylinders once.
BTW, Don.. a page or so back we talked about EGTs and their accuracy vs update time. I talked to the manufacturer of the engine management system who told me it's instantaneous and that the EGTs are monitored only after firing the cylinder.
This system really is on a whole nother level than anything else I've ever worked with including Motec and Autronics. It's strictly a race only setup tho. The data logging capabilities of this unit are phenomenal.. you can really get yourself into data overload quickly with this system. The amount of trims and adjustments in this system are insane. You have gear specific timing tables, gear specific fuel trims, RPM based individual cylinder correction, altitude correction, etc. It's a pretty awesome system.
- Joined
- May 27, 2001
Jay,
I don't think ~35* of timing is out of the question on that type of motor.
John (Mac) from Fast Track threw close to 38* into his alky SBC.
I think it was 10 or 10.5 to 1 compression.
I would see was Steve Petty recommends.
Laz might be able to get you some base numbers from Bill Futch.
I don't think ~35* of timing is out of the question on that type of motor.
John (Mac) from Fast Track threw close to 38* into his alky SBC.
I think it was 10 or 10.5 to 1 compression.
I would see was Steve Petty recommends.
Laz might be able to get you some base numbers from Bill Futch.
At 24 psi boost I'm at 29 degrees at 5200 rpm and 31 at 7400. That seems to work well for me. This is the timing I started out with at the beginning and have not even played with it yet. That's with a static CR of 9.1:1. You will want to be lower, I'm sure.
11:1. Egads!!!
And 35 to 40 psi? No intercooler? You're making me faint. Keep your eyes glued to that EGT.Keep in mind that fast burn chambers do not need as much timing.
