SC finally going back together

True Ken..And Tuning is the one variable that isnt all that easy to do when you dont have thee proper equipment. But unless something is way off the tune shouldnt be doing this. For instance if you had the proper MAF/Fuel injector calibration teh tune should just get you on the money..Not make 80 plus RWHP.

Something else has to be going on or is bad..I could be wrong but I even recall Dav esaying a tune wont gain you massive amounts of power..Which it seems you are missin. Just time to start trouble shooting

I think the a big portion of the missing HP is the lack of advance. The most advance I got was 15 degrees than the knock sensor kicked in and blew out something like 8 degrees. I think at that point I made 235 HP. I have talked to Dave and with the snow injection I should be running 28 to 30 degrees. A lot of HP to be had. The question about there being something else wrong bugs me cuz I cant help but think I am missing something else that is costing me HP. Below are some of the numbers. The AFR was all over the place

Ken
 

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Ken, that AFR doesn't appear to be "all over the place, but it is going lean on top like it's running out of injectors. :eek:

I would need more data to really tell what is going on. A MAF log would be a big help.
 
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I feel for you Ken. I too am involved in a big finger-pointing charade with my broken SC.

Is your SC now fixed? What was broke? I am not to much finger pointing as trying to get as many people imput that i can. My first reaction was to drive the car in the ditch, Second reaction was the car is not worth any more time or money, but the truth is I still love the car, I beleive it can be fixed and I know in the end it will make good numbers.

Ken
 
Ken, that AFR doesn't appear to be "all over the place, but it is going lean on top like it's running out of injectors. :eek:

I would need more data to really tell what is going on. A MAF log would be a big help.

I will see if I can get it from Dan

Ken
 
My first reaction was to drive the car in the ditch, Second reaction was the car is not worth any more time or money, but the truth is I still love the car, I beleive it can be fixed and I know in the end it will make good numbers.

Ken

Ken, you are describing what psychologists call the 'Stages of SC grief'. ;) Regarding my car, I am putting every go fast part I have (which is most everything) onto a nice short mileage stock block. I'll deal with the race engine on the side. I truly hope you get it figured out. Maybe a clogged injector? Done a balance test yet?
 
Ken, you are describing what psychologists call the 'Stages of SC grief'. ;) Regarding my car, I am putting every go fast part I have (which is most everything) onto a nice short mileage stock block. I'll deal with the race engine on the side. I truly hope you get it figured out. Maybe a clogged injector? Done a balance test yet?

Actually havent done anything with the car yet. Just getting some ideas on where to start. The injectors are brand new. I am concerned about Dave comment about it looking like its out of injectors on top end.

Ken
 
Just for a comparision Here are the figures for the tune where I blew the head gaskets. The big blower was the only change. I had 42lb injectors, stock heads and cam. It had about 25 degrees of timing if I remember correct when the gaskets blew. The first 2 pictures are the graph, and figures. The 3rd picture is the figures again for this last tune to compare.
 

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You are not out of injectors, but it had that look to it. ;) Need some useful datalogs. Inj duty cycle vs. MAF voltage would tell an interesting story.

A couple other things that occurred to me that should be looked at.

1) fuel pressure. If it is not rising with boost that will cause difficulty achieving stable AFR and will max injectors very early.

2) Bypass valve. If your bypass valve is not closing or not staying closed under boost for some reason you will never achieve proper boost or power.

I've run into both issues in the past but 15 deg timing is just killing your program. For example I did one dyno pull with 28 deg timing and made 382rwhp and on the next pull accidently left the spout out which locked timing at 10 deg. The car made 275rwhp with no other changes. :eek:
 
You are not out of injectors, but it had that look to it. ;) Need some useful datalogs. Inj duty cycle vs. MAF voltage would tell an interesting story.

A couple other things that occurred to me that should be looked at.

1) fuel pressure. If it is not rising with boost that will cause difficulty achieving stable AFR and will max injectors very early.

2) Bypass valve. If your bypass valve is not closing or not staying closed under boost for some reason you will never achieve proper boost or power.

I've run into both issues in the past but 15 deg timing is just killing your program. For example I did one dyno pull with 28 deg timing and made 382rwhp and on the next pull accidently left the spout out which locked timing at 10 deg. The car made 275rwhp with no other changes. :eek:

Thats what Im looking for Dave useable information about where to start. Thanks. Dan E mailed me that he would get the file to me. I hope tomorrow so I can send it to you before I leave

Ken
 
A couple other things that occurred to me that should be looked at.

1) fuel pressure. If it is not rising with boost that will cause difficulty achieving stable AFR and will max injectors very early.

2) Bypass valve. If your bypass valve is not closing or not staying closed under boost for some reason you will never achieve proper boost or power.

I know I'm way over my head here, so I am just jumping in to give you some feedback on something similar that happened to me. That is why I agree with Dave. Fuel pressure maybe or a significant loss of boost. Not just a small leak somewhere.

When my bypass valve stuck open the only way I found it was because I was passing the 1/8 mark when it happened. Boost stopped at 15, power fell off and I knew something was wrong. But if the car was not moving and I had been on the dyno at the time I never would have known. The only thing that helped me diagnose it so quickly was the fact that my boost gauge has a memory, so I saw it right away.

Now your chart shows a nice straight line out for horsepower, and I see what Dave is talking about when he says the A/F is not all over the place. Not compared to some of the charts my car has made.

What I do see though is less horsepower then we all expected. But if you hadn't given us a list of everything you have done we all would be looking at this and telling you how nice that chart actually looked. Solid horsepower, good torque line and consistant boost and A/F.

So something is robbing horsepower but apparently not affecting any one individual piece of the puzzle. It is affecting everything. Boost. Fuel pressure. Maybe something that would only cause the engine to pull timing.

I would go back to looking for something simple.

Ira
 
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I know just how you feel Ken. I have had many frustrations and setbacks with my SC back in the day. One thing I learned over time is that dyno numbers don't mean ~~~~, and not to get too worried about them. Sounds like you just have a couple small bugs worked out. Once you do, the numbers will come. If there is anything I can help with, just let me know.

Thomas
 
I have a question to the dyno chart. You made your max power around 4400rpm's. Most of these engines with different cams seem to be making peak power higher then that. Did you just start detonating when you got up any higher than 5,000rpms. I definitely see a peak at around 4400 that starts to fall off slowly, why so low of a peak?

I'm sure this isn't related to the problem, probably related to your internal setup, just curious:)
 
You are not out of injectors, but it had that look to it. ;) Need some useful datalogs. Inj duty cycle vs. MAF voltage would tell an interesting story.

A couple other things that occurred to me that should be looked at.

1) fuel pressure. If it is not rising with boost that will cause difficulty achieving stable AFR and will max injectors very early.

2) Bypass valve. If your bypass valve is not closing or not staying closed under boost for some reason you will never achieve proper boost or power.

I've run into both issues in the past but 15 deg timing is just killing your program. For example I did one dyno pull with 28 deg timing and made 382rwhp and on the next pull accidently left the spout out which locked timing at 10 deg. The car made 275rwhp with no other changes. :eek:

I checked the vacuum hose going to the fuel regulator, thinking it had popped off. It looks ok, I cant tell if it is kinked anywhere. I checked the bypass valve. It snaps close after moving it to open position and than letting go. Problem is I dont have any time to check it out at the moment. I leave at noon today. I still have hope it is something simple I am overlooking.

Ken
 
Well Ken if what Dave is saying is true perhaps the timing issue is causing a great performance issue. However the timing is cutting out for a reason.

Perhaps an in car fuel pressure gague is needed to see whats happening on that end. You could very well not be getting enough pressure under boost throwing things off and causing timing to be cut. Have a good trip and dont even open up the sccoa while there!!!!
 
Have a nice Vacation.
Maybe the FPR is leaking? To check it get a gauge on the rail and turn the pump on watch the gauge when you turn the pump off. It should fall off but maintain pressure and not move for a hours. If it falls, then the diaphram is busted.
 
Because these cars won't run with 15 deg timing. Is no one paying attention? :rolleyes: :eek: :p ;) :D :cool: :)

Hmm, i didn't know it would totally change where the power curve is, like that though. Very interesting. I'll start paying attention starting.......now!
 
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