ENGINE for a racetrackoriented MK2

[EGLITOM]

Hi

would this be an engine for a racetrack oriented GT40 MK2 ?

Would it be reliable if detuned a little (700 HP @ app 1000 rpm less) ?

How torque this engines are would they still be at least a little streetable ?

ROUSH/YATES NASCAR ENGINES

or this one

Used Race Engines - Roush Yates

Do you know the sources ( reputation) or any other source for this kind of engine ?

Thanks

TOM

 

[Keith]

Holy Moly! I'd have one just for the bragging rights, but the first ad is for a "non restrictor plate" motor. What Nascar Series would that have been for? For $13,500 - I'd have a go..

For road racing, not sure that the cam/head combination would work too well though....

Aren't these built for flat out 500 milers? By detuning I would have thought they would be reliable and they always use the best parts for sure....

 

[Jac Mac]

Cant speak for Roush, but we have had a good run out of the ones we sourced to date, all of which were converted to roller cams before shipping from USA.

The Yates heads have very efficient ( Tiny ) ports & are surprisingly tractable @ lower RPM. The one that was left over is going into a very different 'Street' car, it will be interesting to 'see' the result, not sure I would like to drive it in anger & I am game for most stuff with 4 wheels.

 

[Mike Drew]

Holy Moly! I'd have one just for the bragging rights, but the first ad is for a "non restrictor plate" motor. What Nascar Series would that have been for? For $13,500 - I'd have a go..

For road racing, not sure that the cam/head combination would work too well though....

Aren't these built for flat out 500 milers? By detuning I would have thought they would be reliable and they always use the best parts for sure....

In a misguided attempt to slow the cars down on the superspeedways such as Daytona, certain races are run with restrictor plates between the intake and the carb. Special motors are built to try to extract the most power with this severe limitation. The advertised motor here is a 'regular' engine, meaning it makes substantially more power. It will also have about 14:1 compression!

The camshaft is probably profiled to produce top-end power at the expense of everything else, so this motor wouldn't be very flexible on a road course, and would be useless on the street. However, a simple cam change would probably improve things radically.

What would be best would be to find one of the engines specifically built for the two road courses that NASCAR runs (Sears Point and Watkins Glen).

While there's no doubt that these race outfits are selling off old engines that have reached the end of their useful life as top-tier racing motors, the quality of the parts inside is outstanding, and they would probably be fantastic at our boy-racer level. The cost to build such a motor from scratch might easily top $50,000, so for sure they represent a bargain.

Having said that, maintenance costs are likely to be quite high, as critical components 'time out' If these engines are raced, valvesprings will need to be changed frequently, and the motors will probably need to be completely gone through every 25-50 hours, tops.

But as a foundation for a detuned street motor, i.e. fitting a less radical cam, and lowering the compression with different pistons, it may be a great place to start.

An even better choice would probably be a NASCAR Busch series motor. These are built to the same standard, but the series has a 10:1 compression limitation (or something like that), which makes them pump gas-friendly. Or so I've been told--I'm happily corrected if necessary!

 

[Jac Mac]

A few things you might want to take into consideration:
1. Rod journals are usually 'Honda' dia.. around 1.6"dia IIRC... I often wonder how they would standup to a life @ lower RPM & operation under different load conditions..
2. These engines I believe are now being phased out in favour of the new 'Nascar only' designs, if that is the case we might not see many more offers of this nature for the Windsor/Yates style ..
3. As Mike points out compression will be the bugbear for any type of street use/pump gas & even if you were to use race fuel you have to be careful how much load you apply @ low RPM. ie ..drive it like a race car, not a show pony!!

 

[EGLITOM]

Thanks guys

Probably a bit too much to handle ( power and servicewise)

TOM

 

[Howard Jones]

Build the lightest weight 500Hp SBF you can afford. Racetrack = light as you can afford on everything.

 

[StanJ]

FWIW, the Winston/Nextel/Sprint Cup engines as well as BGN (now Nationwide Series) have both been limited to a maximum compression ratio of 12 to 1 for several years now. Generally, the combustion chamber in the C3 "Yates" heads mentioned in the ad are most efficient at around 52cc volume with 47-48% squish area, and that would likely be representative of the ones on this engine. Also typical of this head design is it's relatively modest hunger for ignition lead -- 29 degrees or less is common. Taken together, these two factors mean that lowering the compression down to something compatible with 93 octane pump premium (in this engine, probably around 10.5 to 1) without losing TDC charge turbulence (and the attending combustion efficiency that comes with it) is doable with readily available "shelf" pistons from a variety of manufacturers.

As with most other engines, valve spring life in this one would be a function of (a) camshaft lobe profile, (b) rocker arm ratio, (c) valve train mass (not a problem with this engine), and (d) provisions for valve spring cooling (this engine absolutely will have spring coolers). Any camshaft profile suitable for street (or even track use by anyone NOT named Pruett, Kendall, Schroeder, Gentilozzi, etc.) will be far less aggressive that the one this engine was originally built with, even though Cup engines have always been restricted to flat tappet cams. A medium (around .600" at the valve) lift/medium duration (something around 250 degrees at .050") roller tappet camshaft -- preferably a low-lash profile -- would be about right for a strong "play day" engine, but one other factor here is the likely valve job configuration in the cylinder heads: Intake valve seat angle is likely around 52 degrees and the exhaust seat angle is probably closer to 55. These valve job configurations flow like gangbusters from around .400" lift on up but are pretty sluggish from .300" down to seated, a lift range that didn't matter all that much at 9000 RPM down the backstretch at Atlanta but will be far more important to you.

Other internal components like the crank and rods would probably last you sometime into the next ice age, but piston rings -- which are likely around .040" thick for the top and 2nd, would need freshening often if you stayed with the same ring package (I wouldn't).

Jac Mac's point about a Cup engine built specifically for Daytona/Talladega "restrictor plate" events actually being a better starting point has merit -- the heads would likely have ports and valve job angles much more in line with the RPM levels you'd be running, but the bottom end pieces are much lighter seeing as they only have to stand up to roughly half as much cylinder pressure and about 2000 less RPM. Oddly enough, the runners in the intake manifold of the 'plate engine would be far too short for your planned useage -- those engines rarely vary more than 200 RPM during a green flag lap and are tuned for optimum efficiency within a very narrow RPM range.

 

[RG]

First off Roush Yates can build you an engine for your specific application for around $20-$25k complete. They are trying to liquidate their 6010-351 blocks and D3 heads too make way for the new FR9 engines and are really marketing their rebuilt stuff too weekend dirt trackers, drag, and road racers.

Another option is building a 1992-2000 era Ford Nascar engine with ebay parts.
Old Ford 6010-351 block or new Boss 351 block
C3 heads
C3 intake Roush, Edelbrock or Ford Motorsport (Junior Johnson and Roush used Roush. Bud Moore, Wood Bros., Ernie Elliott, Kulwicki used Edelbrock, Yates used Ford Motorsport)
Jesel Rocker system
Crane or Comp Gold race rockers (used without guideplates or girdles by Yates)
used Roush Yates crank
used Lentz or Carrillo rods
JE pistons (Yates and Elliott used JE, Roush Wiseco, Johnson used Wiseco and Cosworth) 14:1-16:1 compression - Perfect Circle rings
H.M. Elliott coated clevite bearings (non-roller cam bearings) (Junior Johnson, Roush, and Elliott used non coated Clevite bearings)
Precision Products piston pins
Precision Products lifter bushings
Precision Products rod bushings
Perfect Circle valve stem seals
Standard Journal camshaft (not 55mm in use today)
Del West or Xceldyne Ti Intake Valves
Manley or Xceldyne SS exhaust valves
Stewart EMP Water Pump
CV Products Fuel Pump
Weaver Bros. Oil Pump (4 or 5 stage)
Used Roush Dry Sump Pan, Aviaid, or custom Moroso pan

around $12-$15k complete including machining of parts if you do your fair share of refurbishing ebay parts with 650-700 hp.

Engines main bearings need to be checked every 10 hrs. and the engine completely gone trough in 20-25 hrs. if you keep it to 8,000 rpm. So you should get 10 racing weekends between rebuilds at 2.5 hrs of all out track time per.

 

[EGLITOM]

Thanks again for this great answers

TOM

 

[Dave K]

Hi Tom,
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http://www.gt40s.com/forum/garage-sale/30806-f-s-358-ford-yates-motor.html
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A few points to note about this motor relative to the discussions above:
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- Not a restrictor plate motor, (and not based on parts from a restrictor plate motor)
- Includes intake and carb
- Lower compression ratio (10.2:1) vs cup motor
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Set-up specifically to run in a Pantera chassis, but would likely work well in GT40 chassis as well. (Custom dry sump pan fabricated to run engine low in chassis but keep oil lines within Pantera frame-rails – which are quite narrowly spaced.)
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If interested, more pics and info here: http://mysite.verizon.net/res0q9zn/parts/id11.html
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<o>Regards,</o>
Dave
detomaso.pantera "at" verizon.net
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