Dynoed my 427so Cobra today.... interesting to say the least!

[neverwouldof]

Originally Posted by John McMahon

I was in the shop when that motor was run in on the dyno, did Fred give you the dyno sheets?

I have driven that car on both the street and track and its got an awesome powerband.

Fred did not drive that car much, so I would start with a complete tune on the dyno.

You got what you paid for, I know that is the engine that was dynoe'd. I watched that car being built from the ground up, all quality pieces.

Do you remember what gear it was pulled on then?

at 3000rpm on dyno it was 18 air/fuel ratio which is strange to me because it flattens out near 4000 into i guess what would be considered normal. Idles around 1100rpm and when driving it acts shaky at anything under 2000rpm.

[Power Surge]

You want whatever gear is 1:1. On most 5 speeds, that's 4th. If the Richmond is different, I am not sure.

[neverwouldof]

Originally Posted by Power Surge

You want whatever gear is 1:1. On most 5 speeds, that's 4th. If the Richmond is different, I am not sure.

Yes i now see on his post that it is a 1:1 ratio for 5th gear and i didn't know that. But i still want to get it checked out before i take it back there to dyno. Wonder what kinda difference that makes... have to research it i guess

Keith

[John McMahon]

Keith,

You must understand that those numbers were on an engine dyono on a stand, those are flywheel numbers. Typically, you will suffer 15 to 18% loss thruogh the drive trains and it sounds like the 1:1 ratio for the RG may suffer some loss too. I don't think the car was ever chassis dynoe'd though.

Don't forget you've got dual 4 barrels there which could probably use a thorough going through. The car sat more than it was driven the last two years or so.

I don't know what Fred did to prep it prior to the sale r what you have done thus far, but I would start with a thorugh tune of the engine and carbs, find the sweet timing spot, get those carbs tweaked and then leave them alone.

[neverwouldof]

Originally Posted by John McMahon

Keith,

You must understand that those numbers were on an engine dyono on a stand, those are flywheel numbers. Typically, you will suffer 15 to 18% loss thruogh the drive trains and it sounds like the 1:1 ratio for the RG may suffer some loss too. I don't think the car was ever chassis dynoe'd though.

Don't forget you've got dual 4 barrels there which could probably use a thorough going through. The car sat more than it was driven the last two years or so.

I don't know what Fred did to prep it prior to the sale r what you have done thus far, but I would start with a thorugh tune of the engine and carbs, find the sweet timing spot, get those carbs tweaked and then leave them alone.

He had the carbs rebuilt during the process of us negotiating.... then he said he had it tuned up by someone nearby. yes i understand the 15-18 loss. but that would be a 34% loss. Hopefully the engine guys down here can help me out....

[Anthony]

Originally Posted by John McMahon

You must understand that those numbers were on an engine dyono on a stand, those are flywheel numbers. Typically, you will suffer 15 to 18% loss thruogh the drive trains and it sounds like the 1:1 ratio for the RG may suffer some loss too. I don't think the car was ever chassis dynoe'd though.

Once you install the engine, with air cleaner - exhaust system, you get a different system than on an engine dyno'd on a stand to some degree. I recently just completed an engine, 427 SO, stock stroke, 0.017" overbore, 10.5:1 CR, about 430 ci. I had built the engine, installed it in my car without ever dynoing it, then had a coolant leak I had trouble finding. Took my car to an engine builder, who fixed my leak, and exchanged my low performance side piipes with higher performance ones, and then chassis dyno'd it, and tuned the carb. The intake is a factory single 4 bbl dual plane, and the carb is an original holley 780 vacuum secondary with Lemans bowels. Initial chassis dyno run had max RWHP 392 and RWtorque 406. After tuning the carb, setting the timing, he then got max rwhp 454 @5900 rpm's and still climbing, and max rwtorque 488 @3800 rpm's. Just for a refernce, he also chassis dyno's roush 427R's, and the best he has ever got was max RWHP 413 and max rwtorque 435.

He said he was impressed with the max torque, and the flatness of the curve. I had asked him about dynoing engines, and he said he likes to dyno them on the stand just to make sure the engine is OK, and get it somewhat close, but he really likes to dyno the engine in the car, to really tune it to the best, with all the equipment installed.

Considering I was using mostly factory ford parts, heads, intake, carb, I figured my engine came out pretty good.

[Hal Copple]

recently my SPF was on a Mustang Chassis dyno for some tuning, basically a 392 Windsor, performer RPM, 750 holley Pro, trick flow heads, match ported, MSD, standard SPF side pipes. roller lifters over a flat tappet A351 Motorsports cam (pretty aggressive). Peak hp was 391 at 4960 rpm, where it also flattened out, peak torque 451 at 4000rpm, pretty flat torque curve. AF ratio was adjusted a bit with jets, althought for street use, i down jetted the primary two sizes, it was just to "gassy" on the street with their rich jetting. It is also a very tractable motor, for street and track.

Just thought i would post what a non-exotic Windsor could put out.

[RACER X #99]

Kieth,
I can back up John McMahons comments on you engine as I was also a witness to the HP and Torque numbers on your engine.The headers used on the dyno pull were from my 427 SO and no mufflers were used. Also I don't know if it was mentioned but 110 octane leaded racing gas was also used during the pull.
I had the opportunity to drive this car and it was one bad ass Cobra. I have 13 years experience driving Cobras on the track and if you need more power than you now have you must be a much better driver than I am. I suggest you send your resume out to one of the teams in need of a driver.

BTW, the Richmond 5 speed is a true 5 speed without overdrive, the first gear is very low and that is why Burtis installed a 2.88 rear in your car. You have the best of both worlds. Good gearing for acceleration and a tall high gear for economy.
I can't figure out why Fred sold that car in the first place.

BTW II I can't understand why guys take their cars on chassis dynos anyway, most are usually disappointed just like you were.

RD

[neverwouldof]

Originally Posted by RACER X #99

Kieth,
I can back up John McMahons comments on you engine as I was also a witness to the HP and Torque numbers on your engine.The headers used on the dyno pull were from my 427 SO and no mufflers were used. Also I don't know if it was mentioned but 110 octane leaded racing gas was also used during the pull.
I had the opportunity to drive this car and it was one bad ass Cobra. I have 13 years experience driving Cobras on the track and if you need more power than you now have you must be a much better driver than I am. I suggest you send your resume out to one of the teams in need of a driver.

BTW, the Richmond 5 speed is a true 5 speed without overdrive, the first gear is very low and that is why Burtis installed a 2.88 rear in your car. You have the best of both worlds. Good gearing for acceleration and a tall high gear for economy.
I can't figure out why Fred sold that car in the first place.

BTW II I can't understand why guys take their cars on chassis dynos anyway, most are usually disappointed just like you were.

RD

Thanks for the info.... I didn't know he was running 110 octane through it at Dyno and with no mufflers and the restrictive 8" filters on top must kill the numbers. However it does need to be looked at because of that lean spike and i need to look into taller 8" filters as well. The way he set the engine in there it has a couple inches room below the hood scoop. Also the car was pulled on dyno in fourth instaed of the 1:1 fifth. So that has some effect. I do like the way he set up gearing, however what is the deal with the clutch and brake placement. Feel like my left knee is touching my chin! it is about 7-8" farther out then gas pedal? Is that normal for contemporary or cobra's in general? can it be adjusted?

Keith