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.

[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....

[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

[DC COBRA]

Man I wished my cobra only loss 18%, I would be pretty ecstatted about that. Mine dynoed 612 at flywheel, but only 442 at rear wheels. Man that is a 28% loss, almost shameful. Got all the goodies to like very unrestricted exhaust, 3.73 gears (they say that makes no difference on dyno figures), Mcleoud double disc clutch(no slippage there), and the good old IRS(BMW). Although nothing to be ashamed of, forget the numbers, this b**ch is fast, fast, fast.

DON

[neverwouldof]

How do these little honda civic 4-bangers dyno out at 500-600hp at the wheels? Nitrous and charging i know but i can't imaging how all the other drive line parts hold up. Guess the engines don't last too long either....

[kris-kincaid]

The IRS diffs in these cars are really lossy when compared to a standard live axle. BTW neverwouldof, thats a nice car you have!

[Dennis Kelley]

Your car has a very big lean spot at 3000 rpms. You may need to do some more tuning on the carb. Its killing your torque.

Later

dennis

[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.

[Anthony]

Originally Posted by gman

1.24:1 4thgear ratio in richmond 5 speed. can you calculate the real hp with this number?

I would think the dyno can calculate torque / Hp in any gear, since the dyno always knows engine RPM's vs rear wheel speed, thus knowing overall gearing, whether you're in 3rd, 4th, or 5th. I would guess that anything other than 1:1 in the tranny will probably lose more HP through the tranny, and I also think you don't want the car geared down too low such that it will spin the rear wheels on the dyno.

[Excaliber]

When I remove the side pipes and bolt on my shortys I can FEEL the difference big time. MUCH faster with the open headers.

Standard TKO type trans could either .6 or .8 in 5th gear, for sure it's overdrive, use 4th on a dyno. With the Richmond running in 4th (not 1 to 1 in 5th) I would expect a substantial drive train loss, that pretty much kills any dyno numbers and puts you back to square one.

[427Aggie]

What air cleaner were you running on the 2 fours when you dyno'd it? If its those little chrome things one for each carb..then I know where some of the power went.

On my ERA I gained over 40 lb of torque from just changing to the stainless pipes with less restrictive mufflers...and 18-20% loss would be about right...Again if you have those 2 chrome air cleaners on the carbs those will suck the life out of a motor because it can't get enough air!

matt

[neverwouldof]

Originally Posted by 427Aggie

What air cleaner were you running on the 2 fours when you dyno'd it? If its those little chrome things one for each carb..then I know where some of the power went.

On my ERA I gained over 40 lb of torque from just changing to the stainless pipes with less restrictive mufflers...and 18-20% loss would be about right...Again if you have those 2 chrome air cleaners on the carbs those will suck the life out of a motor because it can't get enough air!

matt

The sidepipes are less restrictive and baffeled. They are not quiet by any means and were designed to be less restrictive then the sidepipes originally on there. I did question the air cleaners.... they are the double 8" round oil soaked style like K&N. Just looking at them i couldn't imagine getting a great deal of air through. However , what other choices do i really have in that?

Thanks for your inputs!!!

[eschaider]

Look at your A/F ratio. You start to go lean at about 2200 rpm. You reach a maximum lean of nearly 18:1 A/F ratio before 3000 rpm. You don't come back to the ranch until almost 4000 rpm. You have a fuel delivery problem! Don't know where it is but you have it big time. You might check float levels, needle and seat assemblies (less likely). The fuel pump's ability to supply high volumes on short notice, with adequate pressure ...

Engines make power by burning fuel. The more you burn (at the right A/f ratio) the more you make. Timing is absolutely essential to making power, be sure to check out your ignition system.

When you fix it get ready for robust numbers and performance and a lot of driving pleasure. Low speed torque is the stuff dreams are made of.

Ed

[Excaliber]

When I run at the drags I remove air filters and sidepipes and usually change jets as well. If not, I'm solid in the 12's instead of 11's.

[undy]

Originally Posted by neverwouldof

They pulled it in 4th gear up to 7000rpm. It's a 5 gear setup from Richmond. It hit 140mph at 6800rpm in 4th gear. Thats what they showed me....

Keith

...a litlle insight on Richmond 5 speeds... 5th gear is the 1-1 ratio, 4th being similar to 3rd in a standard 4 speed. As Sal said the low gear pull will make smaller numbers. Also.. I'd be a little leary of a shop that didn't know what gear to use, IMHO.

The Richmond 6 spd is Richmond's only over drive tranny. Their 5 speed is a spin-off from the old Doug Nash 5 speed.

Dave

[neverwouldof]

Thanks Guys.... looks like i have a little work to do. I'll be back and post some info of what was done and get it back on the dyno once things are fixed up. I appreciate your input!

Keith

[427Aggie]

Some of the ones I have seen are the large K&N Filters..but to fit under the hoods you need to have a drop base made for the air cleaner...Rob at Keith Craft Motorsports has made a few for some of keith's cars...he can speak more to what the small 8's will do to your power...Also what mufflers are in the pipes..you should see some of the ones that have been taken off...Rob has a brand he replaces SPF's with and gets quite a HP gain.

Matt

[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.