RV8-4:6 Eaton M112 (Throttle Bodies/Butterfly's

[Viper]

Yet another quick question boys. I note most supercharged installations have the throttle body/butterfly aft of the supercharger.

I have made up a twin plenum chamber/cover & inlet manifold has had new set of trumpets shortened to V8 Developments pattern and bored out to 44mm I/D as deep as you can go. I intend to use the existing butterfly's as fitted to the RV8 plenum cover, in my case that is now two, this means they are forward of the blower.

My question is would there be a problem with that Cheers

[Chedder]

Would recon that you will need to sort out some form of bypass either vacuum or electronic from the throttle body to the plenum.

I have been running my Eaton M90 after the throttle body on my efi 3.5 V8 for a year now with no adverse effects other than a poor hot idle due to the length of the inlet tract for the front mounted intercooler, this caused poor airflow on a closed throttle, and has now been resolved with an Emerald ECU and an electronic idle control that bypasses the charger.

Hope that helps

Chedder

[Viper]

Would recon that you will need to sort out some form of bypass either vacuum or electronic from the throttle body to the plenum.

I have been running my Eaton M90 after the throttle body on my efi 3.5 V8 for a year now with no adverse effects other than a poor hot idle due to the length of the inlet tract for the front mounted intercooler, this caused poor airflow on a closed throttle, and has now been resolved with an Emerald ECU and an electronic idle control that bypasses the charger.

Hope that helps

Chedder

Thanks Chedder, I intend to use the standard extra air valve but with two air feeds in & out (from in front of the butterfly's to the plenum cover with a one way valve in each so no loss of psi when the blower comes up to boost rather like a brake servo valve. Well Ill give it a try anyway.

Many thanks Viper.

[Chedder]

Would recon that you will need to sort out some form of bypass either vacuum or electronic from the throttle body to the plenum.

I have been running my Eaton M90 after the throttle body on my efi 3.5 V8 for a year now with no adverse effects other than a poor hot idle due to the length of the inlet tract for the front mounted intercooler, this caused poor airflow on a closed throttle, and has now been resolved with an Emerald ECU and an electronic idle control that bypasses the charger.

Hope that helps

Chedder

Thanks Chedder, I intend to use the standard extra air valve but with two air feeds in & out (from in front of the butterfly's to the plenum cover with a one way valve in each so no loss of psi when the blower comes up to boost rather like a brake servo valve. Well Ill give it a try anyway.

Many thanks Viper.

No problem, tried something similar myself but could not get the spring rates correct in the one way valves, ended up with idle speeds far to high as the charger would not produce enough boost to close the valve until you bliped the throttle, probably due to the fact that I don't run a lot of boost at the moment, more boost from a smaller nose pulley is the next job on the list after the new oil pump It's going to be finished one day......honest!

[Viper]

Would recon that you will need to sort out some form of bypass either vacuum or electronic from the throttle body to the plenum.

I have been running my Eaton M90 after the throttle body on my efi 3.5 V8 for a year now with no adverse effects other than a poor hot idle due to the length of the inlet tract for the front mounted intercooler, this caused poor airflow on a closed throttle, and has now been resolved with an Emerald ECU and an electronic idle control that bypasses the charger.

Hope that helps

Chedder

Thanks Chedder, I intend to use the standard extra air valve but with two air feeds in & out (from in front of the butterfly's to the plenum cover with a one way valve in each so no loss of psi when the blower comes up to boost rather like a brake servo valve. Well Ill give it a try anyway.

Many thanks Viper.

No problem, tried something similar myself but could not get the spring rates correct in the one way valves, ended up with idle speeds far to high as the charger would not produce enough boost to close the valve until you bliped the throttle, probably due to the fact that I don't run a lot of boost at the moment, more boost from a smaller nose pulley is the next job on the list after the new oil pump It's going to be finished one day......honest!

Yes spring strength did cross my mind as well, I also may have the same problem with the PCV set up I have on my engine which currently is tee'd into the brake servo pipe, it has two one way valves, one on the plenum cover now and the other on the servo its self It may be of interest to you re oil pumps and RV8's (Low pressure/high volume) not always desirable in hot weather or track days etc. I have a rather large industrial front cover fitted to my engine (very large water pump) as fitted to some Range Rovers and Military Ambulances, it has a much larger pump (gears are longer) I added a MGB relief spring which is stronger available from R/Steel and packed it out to the same length as the old one which was around 3:5" long. The end result was 75 psi when cold, 50 psi when warm and 15-20 psi on tick over, great improvement over the normal pants reading.

Getting back to Eaton's what was your impression of the over-all power gain after fitting the blower?

[Chedder]

Hi Viper, thanks for the oil pump tip, if my new set up does not improve things, I will give you a shout for more info.
Ref the blower improvements, gained 55hp and 70lbs of torque, peak power is available from 1700rpm through to 5400 before it starts dipping, engine is a bit gutless under 1300rpm but that is probably due to the mapping needing a tweek or it could be symptom of low boost, will find out when I get the new nose wheel for the charger to raise the boost to 7 psi.
The driving experience is excellent, it just pulls like a train when you press the loud pedal, 50 to 120 in 5th is outstanding.
As an added bonus, fuel economy has improved when cruising, up from 17 to over 25 mpg.

Chedder

[Viper]

Hi Chedder, those figures look very encouraging I must say, could you tell me what pulley sizes you are moving up from and what sizes you will end up with to achieve 7-8psi as that's is around the figure I am looking for.

My engine will rev to 7,000 + but I have limited it to 6,600 so as not to bust a piston (ring land) which I have done before showing off

Regards Viper