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tips, technology, tools and techniques related to vehicle driveline components

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HealeyRick
Rick Neville

(489 posts)

Registered:
12/19/2007 05:01PM

Main British Car:
1963 Austin-Healey 3000 Ford 5.0L

authors avatar
Bad Day at the Dyno
Posted by: HealeyRick
Date: September 16, 2015 08:37PM

Motor in my Healey is a Ford 5.0, .30 over, GT40P heads, TFS1 cam, Edel. Performer RPM Air Gap manifold and Holley 570 CFM Street Avenger carb. Dynoed on the builder's stand at 345 hp using four tube headers. Only difference after the installation was using cast iron Tiger manifolds and some restrictive 90 degree turns in the down pipe (see my build here: [forum.britishv8.org] http://i81.photobucket.com/albums/j222/healeyrick/IMG_0164.jpg
Took it on a chassis dyno last week ... 199 rwhp!!!! I was disappointed to say the least. Figuring 20% parasitic loss, I hoped for about 270 at the wheels. So my question is, am I really losing 70 rwhp over the crappy exhaust? I have a set of block hugger headers from Summit that MIGHT fit, but I'm going to have to do a ton of work to find out and they still might not fit. If I went to all that trouble, how much hp do you figure I could gain back? When I was building this car, my target was putting a 271 hp HiPo in the car and my present rwhp is probably not that far away from that. The 345 hp was a big surprise, but it's really close to what the Ford crate motors were turning out. I might go to all that trouble if I could get 70 rwhp, but if it's 20-30, I'll probably leave it as is.



Edited 1 time(s). Last edit at 09/16/2015 08:39PM by HealeyRick.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6468 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Bad Day at the Dyno
Posted by: BlownMGB-V8
Date: September 17, 2015 01:34AM

Yeah, it could be.

Jim


Jim Stabe
Jim Stabe
San Diego, Ca
(829 posts)

Registered:
02/28/2009 10:01AM

Main British Car:
1966 MGB Roadster 350 LT1 Chevy

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Re: Bad Day at the Dyno
Posted by: Jim Stabe
Date: September 17, 2015 02:13AM

The Flowmaster muffler I had on mine had a huge effect on the power causing it to nosedive at 4800 rpm instead of peaking at 5750 which it did after switching to a Dynomax muffler.


Nexxussian
Erik Johnson
Alaska
(62 posts)

Registered:
04/20/2015 10:32PM

Main British Car:
1974, MGB, Citroen Color Rover V8

Re: Bad Day at the Dyno
Posted by: Nexxussian
Date: September 17, 2015 03:15AM

A restrictive exhaust could cost that much.

However, how much you will gain back will depend on the construction of the headers you dynoed it with (flywheel, if I'm reading your post correctly you lost ~70 hp between flywheel dyno and chassis dyno that you can't account for in drivetrain loss).

If your headers were a long tube design, you likely picked up some power from them, that you won't likely recover with a block hugger style header.

Is there any any way to use an RV8 style or "fenderwell" header in a Healey?

I'm planning on similar for my upcoming MGB V8 swap.

Was your 199 at the wheels just a power test, or was there any tuning done to optimize it to the car?

Did you have mufflers installed for the chassis dyno test?


88v8
Ivor Duarte
Gloucestershire UK
(1041 posts)

Registered:
02/11/2010 04:29AM

Main British Car:
1974 Land Rover Lightweight V8

Re: Bad Day at the Dyno
Posted by: 88v8
Date: September 17, 2015 04:29AM

Dynos are not a source of absolute truth.
Not saying a different roller dyno would magically find that missing HP, but it certainly might give a different figure.

And of course, the engine dyno, well, hmmm.

Ivor


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6468 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Bad Day at the Dyno
Posted by: BlownMGB-V8
Date: September 17, 2015 10:45AM

I'm a firm believer in equal length, long tube headers. Very difficult to build in a small space, but rather than hinder the exit of exhaust gasses, if designed properly they Extract the exhaust gasses. That can make a huge difference in output. Never think for a minute that a shorty header or any cast manifold is going to be as efficient as a well designed header. If this was true you would see them on top fuel dragsters and Indy cars. And you never do, do you?

Jim


mgb260
Jim Nichols
Sequim,WA
(2461 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Bad Day at the Dyno
Posted by: mgb260
Date: September 17, 2015 11:52AM

Rick, Look at Doug's Mustang Tri-Y headers also. Seem to fit in tight spots. Engine dyno's are optimistic with gross HP. Chassis dyno's are conservative with net HP at the wheels. Usually 20-25 percent less at the flywheel and additional 15-20 percent less at rear wheels.



Edited 1 time(s). Last edit at 09/17/2015 11:57AM by mgb260.



HealeyRick
Rick Neville

(489 posts)

Registered:
12/19/2007 05:01PM

Main British Car:
1963 Austin-Healey 3000 Ford 5.0L

authors avatar
Re: Bad Day at the Dyno
Posted by: HealeyRick
Date: September 17, 2015 01:32PM

Thanks for all the replies and suggestions. The chassis dyno was a power test through the mufflers. No additional tuning. Mufflers are Spintechs and are pretty free-flowing. Dyno operator didn't feel like additional tuning would help much. It's running rich on the top end, pointing to it being choked through the exhaust. There really isn't a lot of room in the engine compartment, which is why I used the cast iron manifolds in the first place. The block huggers seem to be the only ones that might fit. I eyeballed them further and I'm afraid I'm going to have issues with electric cooling fan interference with the water pump pulley if I drop the motor to get the block huggers to fit under the steering column. I'm beginning to think leaving well enough alone is the way to go, but you all know how tough it is to leave horsepower on the table.


DiDueColpi
Fred Key
West coast - Canada
(1365 posts)

Registered:
05/14/2010 03:06AM

Main British Car:
I really thought that I'd be an action figure by now!

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Re: Bad Day at the Dyno
Posted by: DiDueColpi
Date: September 17, 2015 03:03PM

Those Tiger manifolds are probably the worst Ford manifolds ever made.
They weren't even big enough for the 260 that they were designed for.
So getting the HP that you did was pretty good I'd say.
If you have to keep them. Then port match them to your heads and then send them out to get Extrude honed.
Because you can polish a turd!
It won't equal a LT header.
But the difference will be surprising.

Cheers
Fred


roverman
Art Gertz
Winchester, CA.
(3188 posts)

Registered:
04/24/2009 11:02AM

Main British Car:
74' Jensen Healy, 79 Huff. GT 1, 74 MGB Lotus 907,2L

Re: Bad Day at the Dyno
Posted by: roverman
Date: September 17, 2015 03:04PM

Any possibility to flip the current headers, to dump in front ?


IaTR6
Dennis Costello
Central Iowa
(191 posts)

Registered:
12/29/2007 02:53PM

Main British Car:
'73 TR 6 '97 Explorer 5.0

Re: Bad Day at the Dyno
Posted by: IaTR6
Date: September 17, 2015 05:23PM

Rick, Look at Patriot H8482-1 headers. they are different in that all four tubes are in a flat plane and meet at the collector. If you would like, I should be able to get some measurements for you. I used these on a TR6, where I did not move the engine back very far, and dropped it down instead. It hasn't run yet (so why am I sitting here and not in the shop?) so I cannot give any opinion on their horsepower limitation.
Dennis


HealeyRick
Rick Neville

(489 posts)

Registered:
12/19/2007 05:01PM

Main British Car:
1963 Austin-Healey 3000 Ford 5.0L

authors avatar
Re: Bad Day at the Dyno
Posted by: HealeyRick
Date: September 17, 2015 06:58PM

Here's my concern. This is where the Tiger manifold is relative to the steering column:

http://i81.photobucket.com/albums/j222/healeyrick/IMG_0165.jpg

I had to grind the choke tube away to get clearance:

http://i81.photobucket.com/albums/j222/healeyrick/IMG_0167.jpg

This picture was prior to dropping the motor back into place. I may have 1/4" clearance there, now and I'm not sure a header tube will be able to fit,


Dan Jones
Dan Jones
St. Louis, Missouri
(280 posts)

Registered:
07/21/2008 03:32PM

Main British Car:
1980 Triumph TR8 3.5L Rover V8

Re: Bad Day at the Dyno
Posted by: Dan Jones
Date: September 18, 2015 06:02PM

> am I really losing 70 rwhp over the crappy exhaust?

We did some exhaust testing on a 400+ HP 351C Ford V8. The 351C-4V has cast iron exhaust manifolds with very large ports. Even so, we lost 36 HP and 30+ ft-lbs compared to long tube headers. The worst of the mufflers lost 50 HP compared to the best (Magnaflows). The big lesson learned in that series of tests was that you can throw away most of the power gain a cam/carb/intake swap with a poor exhaust.

> Dynoed on the builder's stand at 345 hp using four tube headers.

Some of the difference can come from higher induction temperature with the engine installed in a vehicle and other losses: air cleaner versus carb bellmouth, accessory drive, transmission, differential, tires etc. Were both dyno sessions converted to standard day conditions?

> The block huggers seem to be the only ones that might fit.

Have you ruled out the FRPP stainless steel shorty headers for fit ? Even the OEM stainless steel shorty headers would be better than those cast iron logs.

Dan Jones


66Vette
Ed Kent

(1 posts)

Registered:
02/15/2014 10:18AM

Main British Car:


Re: Bad Day at the Dyno
Posted by: 66Vette
Date: December 19, 2015 11:02PM

Dan,
Not sure if this thread is still active. I have a Ford 302 and with all the goodies, I computer dyno'd at 305 hp. I have the hugger headers into 2.25 90 degree pipes that empty into chambered pipes. I didn't see where you mentioned the transmission you have, but I have a C4. After dyno, the RWHP was 188! According to the notes I've found regarding HP loss with auto transmissions, the C4 has a 28% loss. that's 54 horses lost with the C4....I'm not happy, but now I don't have to worry much about changing out my rear! Just my 2 cents..
Ed


MGBV8
Carl Floyd
Kingsport, TN
(4511 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB Buick 215

authors avatar
Re: Bad Day at the Dyno
Posted by: MGBV8
Date: December 20, 2015 10:53AM

Ed,

What do you mean by "computer dyno'd" exactly?

I "computer dyno'd"/calculated the RWHP of my Camaro with a Quarter Jr. program & actual 1/4 mile timeslips to be right at 400hp at the wheels.



HealeyRick
Rick Neville

(489 posts)

Registered:
12/19/2007 05:01PM

Main British Car:
1963 Austin-Healey 3000 Ford 5.0L

authors avatar
Re: Bad Day at the Dyno
Posted by: HealeyRick
Date: December 22, 2015 10:46AM

Just a bit of an update. Re: the question of my tranny, it's a Ford T5Z, I'm pretty convinced my exhaust system is robbing the horsepower. I've purchased a set of Summit block huggers: SUM-G9063 It looks like I'll be able to make them fit with a little work. Too cold to work in the garage now, so that will wait until spring. What I'm also thinking of changing is the routing of my right side exhaust pipe. Rather than run it straight out of the back of the car, I made two 90 degree bends to carry the pipe over to the left side to give the appearance of the stock Healey's twin pipes. I like the look, but am afraid those right angles are costing some horespower as well. Will report back when the changes have been made and I get it back on the dyno.


rficalora
Rob Ficalora
Willis, TX
(2764 posts)

Registered:
10/24/2007 02:46PM

Main British Car:
'76 MGB w/CB front, Sebring rear, early metal dash Ford 302

authors avatar
Re: Bad Day at the Dyno
Posted by: rficalora
Date: December 23, 2015 04:44PM

Rick, maybe you can just modify how the exhaust crosses over - a couple of 45°'s instead of 90's?

The other thing to consider is whether you'll really miss the extra ponies. I lost similar when I redid my exhaust - down sizing the pipe, using Spintech's flat mufflers and glasspack resonators. But, even with 225's out back I can still spin the tires in the 1st three gears. I'll eventually redo mine to get some of the hp back, but it's low on the priority list!


302GT
Larry Shimp

(240 posts)

Registered:
11/17/2007 01:13PM

Main British Car:
1968 MGB GT Ford 302 crate engine

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Re: Bad Day at the Dyno
Posted by: 302GT
Date: December 24, 2015 09:30AM

Do you have a cross-over pipe connecting the right and left banks? This can reduce exhaust pipe restrictions since both pipes are available for exhaust flow after the cross-over. But it will not help the header problems of course.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6468 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Bad Day at the Dyno
Posted by: BlownMGB-V8
Date: December 24, 2015 11:52AM

A reduction in HP does not always mean a reduction in torque.
However, exhaust restriction is a really effective way to throttle an engine. I have a Suzuki Samurai that I use on the property that I will bet isn't putting out more than 30 HP. It is very quiet though and the hand made experimental stainless muffler didn't cost me anything as it was off a different project.

Often the biggest restriction we see in these cars is in the exhaust headers just because there isn't adequate space for a decent set of headers. A loss of up to 100 HP there would not surprise me a bit as compared to the dyno headers.

Jim


HealeyRick
Rick Neville

(489 posts)

Registered:
12/19/2007 05:01PM

Main British Car:
1963 Austin-Healey 3000 Ford 5.0L

authors avatar
Re: Bad Day at the Dyno
Posted by: HealeyRick
Date: December 24, 2015 02:09PM

Here's what the block huggers look like. $150 for the pair from Summit. If they work out, I'll spring for
Cerakote:

http://i64.tinypic.com/11vgp5t.jpg

Don't think there's room under the car for either a crosspipe or an alternate way to route the twin pipes. Have you guys noticed, Healeys are LOWWWWWW! To make these fit, I'll have to lower the motor, do some trimming of the footboxes and try to angle the bottom of the radiator forward to give the water pump pulley some clearance. Even then, not sure they'll fit But I think I'll have to give it a shot.

As always, thanks for all your comments and help.
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