Another Dyno thread...

Just did the TFS top end on the Cobra: Twisted Wedges, Stage 1 Cam, 1.6 TFS RR, Track intake, 65mm T-body, 77mm Bullet maf. The dyno numbers are 251hp, 273 tq. My previous numbers are 276hp, 278tq with Gt40's, 1.7's, RPM intake, everything else the same. My block is punched to 306. The TFS dyno was a Mustang and the Gt40 dyno was a Dynojet. I understand the differences in the dynomometers; I don't understand why my gt40's dyno as well as my Twisted Wedge heads. I'm pretty sure that adding the 10% loss to the Mustang dyno that they're about equal. I'm about $3G's lighter in the wallet with only a more reliable (new) set up.Any comments?:shrug:

Thanks
Batman

I see where you're going. Did you have the same cam as before? Are you using the same timing?

The previous cam was and 'E', and the new one is the TFS stage 1. Both set ups were optimized on the dyno. I now run 20* initial, 36# fp. Then, it was 16* and I don't remember my fp. I'm not looking for bragging rights, just the optimum performance for my set up.

thats interesting..

Something has to be wrong. I would have thought the tfs kit would dyno well above that. What was the a/f?

Same MAF? Same position? Whats the a/f ratio? Are the valves seating all the qway? Need shims?

make sure valvetrain is set right.

what's the a/f ratio?

Only thing I want to know is the chamber sizes on the new heads compared to the old gt-40's and the headgasket thickness used. I bet compression ratio probably went down in the upgrade that maybe you werent aware of

That combo should be near or greater than 300 rwhp on a Dynojet. There is definately something wrong. Did you get a wideband on there when it was dynoed? Can you post some dyno sheets and/or af ratios?

I'm not sure what the Gt40's chamber volume is but the Tfs's are 61. The a/f averaged 12.9--witha minimum of 12.6 and max 15.3. My tuning was done at CPP (Conleys Performance Plus-Mustang 1750), my baseline(on the Dynojet) was at Houston Performance. My RR's were set at 1/8-1/4 turn after zero lash. the head gaskets are a Felpro that comes with the kit. I do have 3 dyno sheets; first 5th and final (10th), but I need to scan them in. My first pass, with 41 pounds of fuel (no vac)n and 15* of timing was 245hp and 267 tq, and as I said earlier, my final was 251hp and 273tq with 20* and 36# bof fuel. I did have a 258/278, but trying for more, we were unable to replicate it--I think the heads were getting hot. I did have a cold air kit (PVC that was 3" (or about 2 3/4" id) and it made a 90* to the right, then a 90* to the left before exiting through a 9" K&N. I have since straightened it out and just put my filter on the end of my 77mm bullet (with a partition between the fan.

Sorry for the triple post, The site was extremely slow last nite.

?

54cc or 58cc comes to mind.:shrug:
I would not agree with decking the heads for a blown application for any reason other than making sure they're flat, but not to raise the CR.
Your a/f figure of 12.9:1 seems fat to me with a larger, aluminum headed motor. The fuel pressure seems fine. What are the plugs reading?
Do you think you're able to run more timing since the heads are Al, you've got larger CV, and the added CI?
What exhaust are you running?

Yeah, we're in agreement about the head thing; My builder was talking about decking for a N/A app. The f/p was fat, but the graph would show the f/p range was good--there is a spot on the graph that shows, low, high and average. We never did a plug chop: I'm not a tuner and this wasn't suggested during my dyno time.. Your assumption on my timing may be right. I have long tubes, high flow cats and X pipe that goes out through race magnums (2.5"). Someone asked if I got a wideband and I did.

somthing is "off" trick flow top end kit on my stock cobra motor was 290hp on a dyno jet

I really appreciate you guys' wisdom. I have some more info so I can hopefully sort out my situation. One more thing: my car has an AOD computer-- how significant are the timing curves and other EEC items in this box as opposed to the A9l or P?

the auto's have a more aggressive timing table but no by much. Really shouldn't be a factor in why the power is down.

Thanks Bros!

I believe it also has a different IAC decay rate and something else to do with drivability.