Hey guys, I finally got the car working right after the 4th dyno session. Things always seem to go wrong when your are paying a lot of money by the hour. lol Anyway, the last time were we there we made NO POWER (literally like 93rwhp) and we realized that the timing calibration was off. I'm using an aftermarket ECU, Link G2. So I went home and fixed the issue, we were 23 degrees retarded so that explains the no power issue. I mean I'm not saying we are 100% exact on timing now but maybe only a few degrees off. So then we go back last night and start tuning. We got up to 405rwp which isn't bad but I would expect a lot more from a Heads and MS4 cam motor with 11.5:1 compression and forged internals (stock block and crank).

So my question is should I be running more timing on a large cam. Currently at 29 degrees (give or take a few) at WOT. Another thing that was strange is that the more fuel we gave it, the more power it made. I'm running at 12:1 air fuel instead of 12.8 or 13 like most NA cars would like. Does that me I don't have enough timing or does that mena this setup just likes the fuel? Any help would be greatly appreciated.

Thanks,
Adam

 

12:1 means you are rich..I think the Timing needs to be played with more.

 

You might have a little too much timing in it right now. I'm going to be gone for the weekend, but when I get back I will check. IIRC, my ms4 tune is at 26*. At 28* it did not hurt, but did not help either. I am also on stock compression though. I think because you're higher compression, you'll actually have to run a little less timing if you're on pump gas.

Also, 12.1:1 is too rich n/a. 12.8:1-13.1:1 is probably going to do you better.

 

Thats the strange thing. We were at 13:1 AF ratio and then we added a liitle fuel and it made more power. We went too far and it started to make less power but we found the peak to be around 12.1:1 AF which is too rich for an NA motor, but that is where it made peak power. So does that mean we have too much or too little timing?

I know that raising compression usually means you retard timing but with such a large cam the dynamic compression will lower dramatically. So I'm kind of thinking that we don't have enough timing even though 29* is at the limit (if that value is accurate). I guess we could try backing off the timing a few degrees and see what that does. The tuner mentioned that he had seen head/cam LS1's make 380-400rwhp before. Obviously it happens like in my case but i would think that I should be able to hit the 450-470rwhp range. I do have the Edelbrock intake and 4 barrel TB. I was running their air filter which they say is awesome and flows 1000cfm. I heard from two people that it is crap and so I took it off and gained 10rwhp. If it were a stock filter I could see that but not on an aftermarket one. I also have custom 1 3/4" cross over style headers which shoudl only help. Anyway, the fuel ratio at 12.1:1 is optimum for power according to the dyno, even thought it is rich for what I know.

How would I SAFELY find the right timing. If I keep advancing it will I see a small power decrease before I hurt the motor, or will I run the risk of hurting the motor. I want a conservative tune as I will be road racing it and don't want to kill the motor so quickly, but at the same time I would love to find that additional 50-70rwhp that I think should be there.

Thanks,
Adam

 

What transmission setup are you running and what type of dyno was it? Depending on the answer to these two questions 400HP may be accurate. I'm a bit concerned about the 12:1 AFR though. That makes me think you had some detonation at the proper AFR and adding the fuel helped to eliminate some of it. Try backing the timing down to 24 degrees and optimizing air/fuel your next time on the rollers and see what this does. I'm running 11.3:1 comp and 29 degrees timing with my setup, so I don't think your timing is excessive. But something has to be going on for you to need that kind of AFR.

 

What kind of heads are you running. A more efficient head will usually require less timing.

I have seen some really good heads make peak at 24*-26*

 

5.3LJimmy, Can you explain why a gearbox would affect hp. I'm curious and would like to learn. I'm using an Audi 6 speed manual transaxle. I figured that each transmission woudl have the same HP even though the torque may very depending on the ratio. Obviously an auto would make less then a manual but that is all I know.

I will try to cut back timing to see if that helps the fuel ratio.

SOM, I'm running Patriot LS6 ported heads with the big valves. I wanted a bit less torque for my setup so I don't destroy the transaxle. My tuner said that the heads and cam LS1 he did that was using a porsche transaxle made about 380rwhp but that seems so low.

Adam

 

I was mainly curious to see if you were running an auto with a high stall converter, which would dyno significantly lower than a manual. I can't even guess what the drivetrain loss would be thru the transaxle versus the fbody manual tranny setup, so I can't say if that may be part of the reason for the low numbers. You still didn't say what brand of dyno you were tuning on. Most here use a dynojet which will show higher numbers than a mustang or dyno dynamics. Judging by the numbers from the Porsche I'm gonna say it's likely a stingy dyno. But, I would be less concerned with the numbers and focus on getting the tune lined out.

 

ya im with Jimmy on that a md they say makes around 10-12% less than a dynojet and a auto will read about an 18% loss at the wheels as opposed to like 15% on a m6 from the crank hp. Not sure those are exact numbers either.

 

Well unfortunately it was a Dynojet and a manual trans so my numbers shouldn't be too off. I can see a 10-20 hp difference but 50-60hp sounds a bit much. I'm running an undrive pulley and no power steering so that should only help. The only thing I can think is that the tuning is not optimized (specifically the advance) or the intake (Edelbrock Vic Jr) is not helping.

Would excessive blow-by cause you me to get 405rwhp or woudl it be more dramatic then that. It is the first motor I built so it may not be perfect but it seems to be strong and sound good to me.

 

I am sure excessive blow by could hurt your numbers. 405hp peak is too low for your set up. Just for comparison value, on a stingy Mustang Dyno, i am just a hair under 440rwhp (T56 tranny, MS4, FAST 92/92, PRC stage 1 heads). I still think you have too much timing, checking mine I am @ 26* WOT, on stock compression. Though I have EFI live and did part throttle tuning, I had a sponser put it on the dyno and touch up the tune (a learning experiance as well). Peak horse power is at 6,400rpm, but you should see a very flat torque curve as well (iirc mine was 300ft/lbs + from 3k-6.5k).
I believe timing is much more cam oriented than anything else. Let us know if backing off the timing helped, I'm thinking around 24*-26*.
If not, check your compression. What valve springs, puch rod length, etc are you using?