420a High flow intake manifold options

[wyv344]

Are there any options for a High flow intake manifold for a 2g eclipse 420a engine

 

[VelocitàPaola]

As far as I know, your two options are: 1) fabricate one from scratch, 2) port and polish a stock manifold. There used to be some Chinese-made sheet metal manifolds available. The quality was dubious, and I'm not sure they're still in production.

 

[Clipsoe]

There's this one.

KSR 420a Intake manifold | KSR Performance

This is a sheet metal intake manifold for the 420a. Can be customized for different throttle body setups. This setup is not intended for the stock 420a fuel rail, the Magnus MMCFUL1030 is recommended and can be purchased here as well. (MMCFUL1030) takes an 11mm injector cap not the standard...

www.ksrperformance.com

You can make your own since the 420a mani is a two piece, like this.

custom (from stock) 420a intake manifold - Mitsubishi Forum - Mitsubishi Enthusiast Forums

2nd Generation - custom (from stock) 420a intake manifold - i also just finished this manifold that u see below for a guy by the name of Mark Bullett who currently owns the fastest and most powerful non turbo eclipse. he was running a ported stocker for the longest time and then he recently...

mitsubishiforum.com

Or you can spend some money and get something custom like from here.

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AMMFAB intake manifold info and pricing..... - neons.org

forums.neons.org

I tried getting one of the chinese ones for my 420a at the end of last year and nobody makes them anymore, so your options are as above.

 

[BLACK'98DSM]

I looked into getting the stock one extrude honed. I was told that they could only do that with the lower half, which leaves the upper half to be done by hand.

Have you upgraded the throttle body and ported the plenum yet? That's the best bang for buck without digging deep in the head work.

 

[wyv344]

I looked into getting the stock one extrude honed. I was told that they could only do that with the lower half, which leaves the upper half to be done by hand.

Have you upgraded the throttle body and ported the plenum yet? That's the best bang for buck without digging deep in the head work.

I haven't done any porting yet. I'm in the process of rebuilding my 420a with forged internals (pistons, rods, bearings) and wanted to know my options to increase the horsepower

 

[BLACK'98DSM]

If you get a 60mm throttle body and port the plenum to 59mm it will flow plenty of air. Do a mild port & polish on the head too since it's already off. The head ports and the throttle body are the 2 biggest limiting factors of airflow on the 420a from the factory.

(59mm to prevent boring through the walls)*

 

[BLACK'98DSM]

This is what I mean by a mild port and polish (my cylinder head). Gasket matching the head won't do any good if your intake manifold isn't also gasket matched. If you're gasket matching both, then more power to you

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I'm also curious if you have a way to tune yet. If you run out of fuel on the stock computer it sucks.
Upgrade the fuel system = rich idle
Stock fuel system = lean acceleration
(You can't tune the stock ECU, fyi)
It takes a lot of airflow to max the stock injectors but the fuel pump runs out pretty quick, in my experience.
You can use an SAFC on these cars but it's not very efficient or reliable.

Here's gasket matched instead of mild (also my cylinder head):

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Oh and I almost forgot the cams. The stock camshafts don't have enough duration to move a "high performance" amount of air.
And with upgraded cams your stock springs will shake or float, so you need to upgrade those if you want to efficiently move air until rev limiter. Again, the tune is important.

It's all about how the parts will work together on these engines. If you get more air in, you need to get that much air back out. They're comparable to an air pump in a way.

 

[wyv344]

This is what I mean by a mild port and polish (my cylinder head). Gasket matching the head won't do any good if your intake manifold isn't also gasket matched. If you're gasket matching both, then more power to you

You must be logged in to view this image or video.

I'm also curious if you have a way to tune yet. If you run out of fuel on the stock computer it sucks.
Upgrade the fuel system = rich idle
Stock fuel system = lean acceleration
(You can't tune the stock ECU, fyi)
It takes a lot of airflow to max the stock injectors but the fuel pump runs out pretty quick, in my experience.
You can use an SAFC on these cars but it's not very efficient or reliable.

Here's gasket matched instead of mild (also my cylinder head):

You must be logged in to view this image or video.

Oh and I almost forgot the cams. The stock camshafts don't have enough duration to move a "high performance" amount of air.
And with upgraded cams your stock springs will shake or float, so you need to upgrade those if you want to efficiently move air until rev limiter. Again, the tune is important.

It's all about how the parts will work together on these engines. If you get more air in, you need to get that much air back out. They're comparable to an air pump in a way.

I was considering getting an AFX aftermarket ECU, and luckily there's a tuner shop 30 mins away from me

 

[BLACK'98DSM]

I was considering getting an AFX aftermarket ECU, and luckily there's a tuner shop 30 mins away from me

I can't speak on the quality or functionality of an AFX ecu for a 420a. But I can definitely say a MegaSquirt will be more supportive.
The AFX is an outdated solution for the 420a's it seems like.

 

[wyv344]

I can't speak on the quality or functionality of an AFX ecu for a 420a. But I can definitely say a MegaSquirt will be more supportive.
The AFX is an outdated solution for the 420a's it seems like.

I was looking at other options besides the megasquirt for the 420a because i don't have a lot of experience dealing with wiring, but it seems that i'll have to do some research on it in order to set it up correctly with no issues

 

[wyv344]

If you get a 60mm throttle body and port the plenum to 59mm it will flow plenty of air. Do a mild port & polish on the head too since it's already off. The head ports and the throttle body are the 2 biggest limiting factors of airflow on the 420a from the factory.

(59mm to prevent boring through the walls)*

Can you use a throttle body from any Jeep on a 420a?

 

[BLACK'98DSM]

Can you use a throttle body from any Jeep on a 420a?

It has to be a 4.0L jeep. Late 90's I believe.
One way to tell if the year model will work is to look at the IAC and TPS and see if they're similar to the 420a.

And I know at one point a couple different places sold billet 60mm throttle bodies for the 420a. The production on those has probably dwindled or stopped but it's worth looking into if you're not comfortable modifying the Jeep TB or just want something fancier.