pat57woods

I'm in the process of putting a 12a from a 81GSL into a MG Midget. I have headers for it and no need for emmissions or even much of a muffler as far as that goes. What gain can I expect from going to a Holley set up over modified stock carb?

TiViD

is it the RB Holley?

pat57woods

The intake is RB but not the carb.

Naegleria_Fowleri

With adding a Holley (according to racing beat) you can expect an additional 20 horsepower with the use of headers and exhaust. That is for the racing beat holley though. I don't know what cfm or anything your holley is, so we really won't have much clue at all.

Also this is with use of a 6 psi fuel pump, and on stock engine. If porting is done the gains depend entirely upon port sizes.

pat57woods

From what I've read elsewhere on this forum that just ditching the emmsion crap and doing the exaust will give you the 20hp. So that tells me that the Holley doesn't give you anything over the stock carb.

jim_chung

iTrader: (2)

I think the previous previous message meant 20 bp gain over stock carb and headers. A holley with stock manifold and restrictive stock exhaust will not have any benefit. So your MG setup should produce about 120 bp at flywheel, with a Holley it should give 140, conservatively. Porting is where the big NA gains come from in a rotary - upwards of 230 bp but becomes undriveable on the steet.

Naegleria_Fowleri

Well also in order to have a holley on there, you have to have all the emissions crap already off. With use of the headers/exhaust the carb should yield a 20 hp gain over what removing the emissions did as well. Sorry I should have been a bit more clear.

MattG

iTrader: (2)

I dont think you are going to see a 20hp gain form removing the emmisions.

But what they say is right in order to get the extra 20 hp, you are going to need to have a good fuel system, free flowing exhaust, etc etc.

Latin270

What size Holley? You dont need a RB prepped Holley for it to work but you do need the RB intake.

pat57woods

Don't have the holley yet, just considering buying the intake. If I do what size Holley should it get?

trochoid

iTrader: (6)

First, do you like Holleys, know how to tune them? Another option is a Mikuni, Weber, Dellorto 2 barrel carbs. What is the intended use for the MG?

pat57woods

The Holley option is based on the good deal on the intake.

pat57woods

The MG is a $2007 Challenge car for the Grassroots Motorsports Magazine challenge. So it will have very limited street use.

trochoid

iTrader: (6)

465 cfm seems to be the best suited for a stock port 12A, but it will take some work if it's not an RB modded one. Can't help with the mods though, not up on them.