Refer to:

http://www.performanceforums.com/forums/showthread.php?t=67260164&highlight=phenolic

Very interesting, and something I've never seen before... Considering we have the only Magna/380 club on the internet, why hasnt anybody here seen this?!

"Ran it yesterday on the same dyno, and it delivered a full 12kw more at the treads with the air duct and the spacers. We then swapped the small air duct back on it and it dropped just over 2 kw.

That means the spacers were good for 10kw!"


I love how AMC has such a following on the greater internets...
"I'm not going to let on to the 380 clowns until I'm 110% positive the gain is real and repeatable."

Would this work for the 74?

Not sure, but I'll be asking the machining contractor at work if he can make some for me

Interested Benny. if you need to do some "EXTRA TESTING"

No worries Waz, could be a very worthwhile 380 "Must Do" mod...

I believe these have been discussed on AMC and quite heavily bagged out by some people due to a lack of proof in the claimed performance figures.

Search hard and you will find it.
eg: http://www.aussiemagna.com/forums/showthread.php?t=69711&highlight=phenolic
and Barry's post which is the person with the controversy on this site
: http://www.aussiemagna.com/forums/showthread.php?t=38061&p=554330&viewfull=1

I've got a phenolic spacer on my 380 N/A & now blown & makes no noticable difference besides the manifold takes a little longer to get hot to touch.

I believe these have been discussed on AMC and quite heavily bagged out by some people due to a lack of proof in the claimed performance figures.

Search hard and you will find it.
eg: http://www.aussiemagna.com/forums/showthread.php?t=69711&highlight=phenolic
and Barry's post which is the person with the controversy on this site
: http://www.aussiemagna.com/forums/showthread.php?t=38061&p=554330&viewfull=1

There is a difference though. Barrys mods were for reducing heatsoak, these mods are increasing the intake runner length dramatically.

Ben just go all out mate, whack a bike TB on each cylinder and go from there haha

Haha nah, I still want my cruise control!!

I installed an RPW phenolic spacer on mine about a year ago, purely in an attempt to reduce heatsoak and intake plenum temps.

It made absolutely no difference to the performance, and it seems to have reduced intake plenum temp (going just by touch) only when the ambient temperature is already cool.

In summer it still gets very hot under the bonnet, including the intake plenum.

Overall probably a waste of time & money, at least as far as reducing heatsoak goes (and yes I have fitted special washers to the bolts).

Even with only a single 3mm spacer I had trouble getting the driver's side rear mounting bolt (on the back of the plenum) to line up with/in the mounting bracket, so who knows how this guy has bolted up the back of the plenum with something like 31mm extra height. Either he's made up new brackets or he's not bothered with the three rear mounting bolts.

Read the link!! The inlet runner length has been increased to the point it nearly touches the bonnet. Nothing to do with temps

Read the link!! The inlet runner length has been increased to the point it nearly touches the bonnet. Nothing to do with temps

:yeahthat:

Most of the heat would come off the exhaust and radiator I imagine - blasts over the top of the engine and down the back, as well as going under the engine. Some venting at the back of the bonnet and a heat shield to block the top flow would probably do more than some spacer that slows heat transfer from the engine itself to the intake manifold.
Any change in engine characteristics would come from changing the inlet runner, and any turbulence the transition points cause/remove.

I did read the link. All of it. I know the discussion was 99% about intake runner length, turbulence etc. I was just adding my 2c worth about heatsoak (doesn't help much if at all) but mainly to point out that if you try the same thing you will have problems with the rear mounting brackets & bolts. I had trouble with a mere 3mm, an extra 31mm must mean you either need to fabricate new brackets or forget about the rear mounts altogether (which can't be good for the stability of the plenum). An extra complication that should be factored in.

What about just getting a die grinder and opening up the holes of the rear bracket a few mm??

Longer runners more torque less top end power. Thats an old post Ben. I did get a set of spacers from MS-75 and conducted a back to back test on the dyno which he was unable to do. no power was found. Had conducted a test a MMAL with 25mm and 50mm spacers on a 6G75 and got the same result loss of top end power but more torque lower down. What will help top end power would be to shorten the runner length.

Break out the hacksaw Ben. Cheers Dave

I did read the link. All of it. I know the discussion was 99% about intake runner length, turbulence etc. I was just adding my 2c worth about heatsoak (doesn't help much if at all) but mainly to point out that if you try the same thing you will have problems with the rear mounting brackets & bolts. I had trouble with a mere 3mm, an extra 31mm must mean you either need to fabricate new brackets or forget about the rear mounts altogether (which can't be good for the stability of the plenum). An extra complication that should be factored in.

As to getting the rear mounting bolts in, if the problem is what im imagining (can't get a long enough bolt in the hole because the head hits the runners where they head towards the firewall) he may have put studs in the lower manifold, put the spacers and upper manifold on, and put nuts on the tops of the studs.

As to getting the rear mounting bolts in, if the problem is what im imagining (can't get a long enough bolt in the hole because the head hits the runners where they head towards the firewall) he may have put studs in the lower manifold, put the spacers and upper manifold on, and put nuts on the tops of the studs.

Correct! :io:

the better option would be to source the upper intake plenum of a jdm diamante like mine, they have the two runner lenths, long for low down torque and at 4000rpm changes to short runners as a electric motor closes a set of butterflys in the plenum. Best of both worlds. Its a set switch over so should be easy to set up and would bolt strait on

Yeah some Pajero's run them also.....dont know how theyre operated though.

Yeah some Pajero's run them also.....dont know how theyre operated though.

Just an extra ECU function.

yeah there is a motor with a worm drive gear that opens the row of butterflys at 4000rpm, found this out by checking its operation-unbolted motor and then revved car up till it reached the set rpm. id say you could set up a switch even and just manually switch it when you want lol. heres a pic, you can just see how the manifold curves under, and the join where the butterflys are housed
http://i694.photobucket.com/albums/vv302/robssei/95%20Diamante%2030M/Image1056.jpg

mmmmmm would this fit a 380 manifold? it LOOKS like it would be close, although the turn to the airbox would be sharper, that can be sorted tho.... oops I just went to half mast...

hmmm could do, i dont know why more of you guys dont fit them to the 3l and 3.5l, would be a direct bolt on, would love to see a dyno tune with one done. I was going to do this mod to my sohc 3.5l before i got the 30m

Would you be able to source one robssei? I'd be happy to give some extra $$ to you if you did the hard yards to bring a couple over?

could do, would have to check pick a part, im fairly certain they were on all dohc 6g7 engines, will see what i can find. should be able to get to pickapart on saturday