RV8 induction mods

[Graham]

As it too cold to work in the garage and the workshop ( shed) is warmer Im playing around with the induction for a 4.6 im putting together. I've got a spare inlet manifold and a couple of trumpet bases 2* pre gems plenums and 1 gems plenum.

I think Im going to use the gems plenum as it has a little less shrouding and more volume. just trying to decide if i try and bugger about and increase the throttle size. it looks like the max is 72mm but that means grafting a new air hose connector on as the od of that is around 72mm. playing with my calipers i reckon 69/70 leaves enough meat on the connector whilst still upping the throttle from 64/65 as stock. any thoughts there.


the trumpet base and manifold would seem sensible to take to 45mm just need to find some trumpets, and a little bit or port matching to the heads..

the heads will be fairly stock to start with, probably just match inlet to the gasket and any obvious casting marks.

cam wise probably something like a stealth.. planning to deck the block to get the gr up from the 4.6's stock 9.35:1

I'll run the whole thing most likely on an emerald so will do away with the afm and run just on tps with maybe a map sensor to trim things... I ran the chim for years on the road on just tps with no issues before and the tuscan is tps only as on tb's

anyone got any pointers on my induction plans..

cheers

G

[GasMunkey]

If it was me and I was going to start again, I would do this

[Graham]

having 2 spare trumpet bases I might well try blending one. fill the holes with epoxy metal, bore to 45mm and the countersink them to create a bell mouth, need to find out what angle to try on the blend though..

cutting and welding a plenum to take a tb is also a possibility, whats the act run 2 *57mm although sorting a tb might be expensive... and the aim here is low cost... i suppose i could cut up the 2 plenums and make a twin,

[GasMunkey]

Google lt1 throttle body

[Graham]

mmm might see if i can get a mate in the states to ship one for me. so nice new stuff for not a huge amount on us flebay 2nd hand stock should be a few $

G

[griffdude]

Graham, have you seen this-
http://www.mez.co.uk/ms12.html
Just about every N/A permutation.

Interesting that it says that the blended base lost about 10hp against the superflare trumpets.

I'm thinking the LT1 TB with the ACT superflare trumpets might be a good combo.

[GasMunkey]

The 10bph loss was with the plastic egg crate insert blended base iirc

Not the same as the one I posted

[Slow M]

Graham said:

...sorting a tb might be expensive... and the aim here is low cost... i suppose i could cut up the 2 plenums and make a twin,

Look up Imfinity Q45 TBs.

Best,
B.

[SILICONEKID340HP]

Is there anyone else running a modified throttle body ? It would be nice to see some positive results .

I know Peter is our Cavia porcellus so i hope it all works out .

[dnb]

Mine uses 2x classic Impreza throttle bodies, plus a few other changes. All in all, the gain was worth while.

[macdeb]

dnb said:

Mine uses 2x classic Impreza throttle bodies, plus a few other changes. All in all, the gain was worth while.

pictures

[griffdude]

macdeb said:

dnb said:

Mine uses 2x classic Impreza throttle bodies, plus a few other changes. All in all, the gain was worth while.

pictures

here-

http://www.mez.co.uk/ms12.html

[griffdude]

dnb said:

Mine uses 2x classic Impreza throttle bodies, plus a few other changes. All in all, the gain was worth while.

What do you recon the gain was? Really interested in the 'dual plane' type inlet manifold & contacted Lloyd Developments & their version was £1995+vat or £2995+vat complete kit fitted.

[Graham]

If i was spendin that much id go for john eales crossover system with tbs !

[Bluebottle]

Graham said:

If i was spendin that much id go for john eales crossover system with tbs !

didnt Steve Heath giunnea pig that setup for JE using Jenvies...i beleive it made 375 bhp?

[Graham]

Bluebottle said:

didnt Steve Heath giunnea pig that setup for JE using Jenvies...i beleive it made 375 bhp?

Not sure, but Im sure i heard it gave an improvement in torque rather than bhp over the setup I have on the tuscan which is je manifolds and 48 downdraft jenvey's we've had 375 out of that setup with the griff 500 bottom end, with cre cam and heads.

As an aside when i went to individual TB's on the race motor there was a small increase in power but a massive difference in the way the engine picked up..

[dnb]

macdeb said:

pictures

As requested:



Gain was about 60bhp at the top end, noticeable torque increase through the entire range and way better manners from low RPM.

[eliot]

GasMunkey said:

The 10bph loss was with the plastic egg crate insert blended base iirc

Not the same as the one I posted

Plastic egg crate indeed! - It seemed like a good idea at the time. I had stopped making them but was asked to make one more and indeed it was 10bhp down on ACT superflares.

I'm not sure whatever happened to the one shown above where i filled the base with epoxy and milled flares directly into it - certainly the photo above isn't directly from my site, so I assume that its from the current owner! Not sure if it worked or not - but I considered it to be far better than TVR's Taraka bodge job.
In all cases I think common sense would suggest that trumpets such as the ACT ones are what you need.

[GasMunkey]

Eliot

I did nick it off your site

You might want to add this
http://www.pistonheads.com/gassing/topic.asp?h=...

[eliot]

GasMunkey said:

Eliot

I did nick it off your site

You might want to add this
http://www.pistonheads.com/gassing/topic.asp?h=...

Interesting project. Not really convinced you need much more than 72mm on a plenum. My late friend who had a griff 500 pulled 285bhp at the growl on a 65mm plenum - that had a slight delta to ambient pressure, but not much. To be fair he ran it with no airhose at-all. With the airhose and airbox I think it was around 85kpa - so clearly thats where to focus your breathing mods.

Anyone with an aftermarket ECU should be able to measure the MAP pressure in the plenum at WOT - if you are getting over ~90kpa then you aren't going to gain much more fitting bigger throttles and indeed it could end up being a pig at low speed due to lack of air speed.

Keeps us busy on a cold night i suppose!