Intake riser

Splinter · Post by **Splinter** » Wed Jul 11, 2007 6:45 am

By bending up custom fuel lines, doing custom PCV routing and switching to WRX power steering and coolant crossover, Ive given myself just enough room to run the intake for the turbo under my EJ20G manifold, but its really cutting it close, and the piping is going to rub like crazy.

If I took my intake gaskets to a fabrication shop, and had them cut me out some 3/8 inch thick aluminum spacers to match the gaskets, put a gasket above it and below it, and used slightly longer bolts, does anyone see any reason for something to go wrong?

Id go higher, but Im worried about interference with the hood.

Threshld1 · Post by **Threshld1** » Sun Jul 15, 2007 1:34 am

well some of the local club guys who started a small company called grimmspeed have started fabricating phenolic spacers for 02+ turbo motors (using new gaskets on the block and intake side of the spacer) to reduce heat transfer from block to intake manifold with no issues. So i dont see why using aluminum spacers would make any difference in performance for what your trying to do. Though I dont know enough about flow dynamics to tell you if the minute extra intake manifold volume is going to affect anything.

evolutionmovement · Post by **evolutionmovement** » Sun Jul 15, 2007 4:29 am

The optimum rpm for intake pulse tuning will drop slightly. Can't see any problems.

Splinter · Post by **Splinter** » Sun Jul 15, 2007 4:35 am

Im running standalone EC, so that's a non-issue

evolutionmovement · Post by **evolutionmovement** » Sun Jul 15, 2007 2:47 pm

I don't see how the EC would make a difference to the pulses since the distance/time they have to travel from the intake valve to the plenum and back to the intake valve for when it opens is fixed. Do you mean tuning the engine to optimize it? I don't think 1/2" or so will make much difference and you're running a turbo anyway, so pulse tuning in the intake is not really important.

Splinter · Post by **Splinter** » Sun Jul 15, 2007 6:19 pm

Yea, I meant adjusting the timing of the pulse slightly, but honestly I dont know enough about that stuff

skid542 · Post by **skid542** » Sun Jul 15, 2007 7:31 pm

What's the difference between a throttle body spacer and a space right at the intake/block junction?

I don't think it'll be a problem.

evolutionmovement · Post by **evolutionmovement** » Sun Jul 15, 2007 10:27 pm

The pulses from the head to the plenum will be most powerful. Pulses from the throttle body back or forward would have little to no power. When a pressure wave hits a different volume, it reflects back. In this case, from the intake valve to the plenum. It's how high rise manifolds old muscle car guys brag about work - the longer runners mean the pulses take longer to travel the greater distance out to the carb and back to the intake valve, so the engine speed where the returning pulse would best help pull air into the combustion chamber through the opened valve for that cylinder's next cycle would be lower. The reverse is also true, with shorter runners offering their minor 'supercharged' help at a higher engine speed.

AWD_addict · Post by **AWD_addict** » Mon Jul 16, 2007 8:28 am

You might as well go with phenolic spacers since you want extra clearance for intake piping and they couldn't hurt.

Like evolutionmovement said, changing the pulse is less significant since it's a forced induction engine.

Splinter · Post by **Splinter** » Mon Jul 16, 2007 3:12 pm

Have you ever seen any sold for the ej20g anywhere?

AWD_addict · Post by **AWD_addict** » Tue Jul 17, 2007 8:50 am

No, but I think there were a set on a 20g that Jake tore down a while ago. Maybe a Japanese company sold them?

You could ask a vendor to make some for the 20g, there are enough 20gs around that they would probably sell out.

Splinter · Post by **Splinter** » Tue Jul 17, 2007 3:29 pm

and unless Im mistaken the EJ25D uses the same flanges on the intake manifold as the EJ20G

All_talk · Post by **All_talk** » Wed Jul 18, 2007 2:05 am

Splinter wrote:and unless Im mistaken the EJ25D uses the same flanges on the intake manifold as the EJ20G

Yep, my EJ25 DOHC heads match right up to my EJ20G intake.

Gary

Splinter · Post by **Splinter** » Thu Jul 26, 2007 7:21 am

The domestic wrenchers at my work suggested getting spacers cut from gumwood, a hard wood...

Apparently thats the most common thing for blown dragsters

n2x4 · Post by **n2x4** » Thu Jul 26, 2007 1:33 pm

I've heard of wood spacers being used on motors before. I wonder how they would hold up in the long run though.

Splinter · Post by **Splinter** » Thu Jul 26, 2007 3:36 pm

Well its not like its terribly hard to take them out if they do wear out I suppose

All_talk · Post by **All_talk** » Thu Jul 26, 2007 6:07 pm

I wonder if moving the injector away from the back of the valve will have any noticable effect. Will it focus the spray pattern on the opposite runner wall? I doubt it would have much affect at higher velocities but maybe at idle?

Just a thought.
Gary

n2x4 · Post by **n2x4** » Mon Jul 30, 2007 9:05 pm

I saw a Edelbrock wood carb spacer when I was at Summit Racing over the weekend. I guess if they make it and sell it, it can't be that bad. I vote you try it out.

BXSS · Post by **BXSS** » Tue Jul 31, 2007 3:14 pm

I think someone may have said this above, but making the intake runners longer will shift the powerband down the rpm range (peak power @ lower RPMs).
This may be very slight in your case since the spacers are small.

vaccine · Post by **vaccine** » Mon Aug 06, 2007 11:02 am

i ended up doing something similar.
but fitting a v3 sti manifold instead so can use the silicon under intake. need to swap a couple of wires on the TPS and done. should make some better gains, especially concidering the EJ20G intake manifold is an abortion of an intake compared with the v3. you'd be lucky to get 2 fat fingers next to each other into the ports. the v3 are massive.. would be good to get some flow testing, but have no idea where.

Splinter · Post by **Splinter** » Mon Aug 06, 2007 7:01 pm

Ive got an RS-RA manifold, its majorly ported.

vaccine · Post by **vaccine** » Mon Aug 06, 2007 9:28 pm

sweet as then.. mate has one of those..
the ports are pretty good as well. and hand finished.

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Intake riser

Intake riser