Best Engine Case for a vinatage race motor?

jwerion · 10-10-2008, 02:08 PM

Hello,
I am having trouble deciding on which engine parts to keep and which to sell, I plan to build a 2.5 ltr ST motor or a 2.8 ltr RSR motor. The plan is to run this in a street legal track car that I plan to build for my wife to do DE events but I would like to run a few Vintage races as well.
I am not really after exact historical accuracy but it will need to be legal in some vintage class or exhibition class. (VARA, RMVR, HSR, etc)

I have in inventory;
Mag Chain boxes,
Mag fan housing,
Mag 2.4 MFI cam towers,
Mag MFI throttle bodies & stacks,
Mag 2.4 7R case
Early aluminum 2.0 ltr case
Mag & Plastic 2.4 S Throttle bodies and stacks
2 Bosch MFI Pumps model 015
66 Mm conter weighted crank.
3.2 ltr oil pump

What motor should I build and which parts should I keep to build it.
Thanks for your help

Steve@Rennsport · 10-10-2008, 07:51 PM

Hi,

Use all your mag parts except for the 7R. Use your early Aluminum case and have it modified to take the later intermediate shaft bearings and late chain boxes.

Use the Mag stacks; open them up for a 2.8.

I'd use a 930 oil pump if it were me, for much better scavenging (that means more HP).

jwerion · 10-10-2008, 08:34 PM

Steve,
thank you for the advise this is the way I was leaning but I wasn't sure the mag parts would fit the older aluminum case. I am curious about you sugestion to use the mag MFI stacks and throttle bodies over the 2.4 S units can you explain to me why this is the best way to go and who might be able open up the stacks to work with a 2.8 RSR motor
Thanks for the info

Steve@Rennsport · 10-10-2008, 11:42 PM

The early cases can be modified to accept the later mag (or AL) chain boxes to reduce the chance of oil leaks.

Mag stacks flow better than plastic ones and can be enlarged much easier than plastic stacks. For a 2.8 race engine, this is quite important but ultimately will depend on your choice of camshafts. You didn't say what cams you plan on using so I cannot offer anything specific.

Bear in mind that 2.8 RSR engines used tall-butterfly stacks with 50mm throttles mated to those special heads that had 42mm ports with 46mm valves.

jwerion · 10-11-2008, 07:33 AM

Steve,
I am not ready to build this moter, so I have not given cams etc much thought I am just clearing out the garage and wanted to make sure I keep the things I will need to build the motor down the road.
Will some one be able to modify the 2.0 ltr MFI throttles that come with the mag stacks to 50MM or am I looking at buying different units. I have seen the High butterfly units you speak of but they where around 12K if I remember correctly and this will be out side of the budget most likely. I assume my mag stacks cannot be modified to a high butterfly set up?

What heads should I start looking for that can be modified to match the special 2.8 RSR heads you spoke of? If I go with the 2.8 RSR motor I assume you I would need a 2.7 crank and not the 66 MM crank I have now?
I assume you can build a 2.8 RSR motor like this do you have any idea of what it might cost?

Steve@Rennsport · 10-11-2008, 10:27 AM

Quote:

Originally Posted by jwerion

Steve,
I am not ready to build this moter, so I have not given cams etc much thought I am just clearing out the garage and wanted to make sure I keep the things I will need to build the motor down the road.
Will some one be able to modify the 2.0 ltr MFI throttles that come with the mag stacks to 50MM or am I looking at buying different units. I have seen the High butterfly units you speak of but they where around 12K if I remember correctly and this will be out side of the budget most likely. I assume my mag stacks cannot be modified to a high butterfly set up?

What heads should I start looking for that can be modified to match the special 2.8 RSR heads you spoke of? If I go with the 2.8 RSR motor I assume you I would need a 2.7 crank and not the 66 MM crank I have now?
I assume you can build a 2.8 RSR motor like this do you have any idea of what it might cost?

Understood. Cam choices are critical to the overall success of the motor so give that plenty of thought before making any purchases. In a nutshell, one configures the intake system, exhaust system, and cylinder heads around the RPM range that the engine will run in.

The street MFI throttles and stacks can be opened up somewhat for such engines but not close to the RSR setup.

A 2.8 RSR motor is comprised of 92mm P/C with a 70.4 crank. Using a 66mm crank yields a 2.6. One can also build a VERY robust 2.8 using a 3.0 Turbo case, your 66mm crank and 95mm P/C's. This combo offers heads that closely replicate those very special 2.8 RSR ones, too.

You need to choose camshafts before making any decisions about intake system configuration, especially if this will be a race engine since throttle position really affects how it will run in the mid and upper RPM ranges.