seized

Hi folks,

I recently have had my 1.5 mirage converted to 4g15 dohc 16 valve engine since the original engine mysteriously died.

My question is, anyone else have this engine and what mods can be done?

Also is Unichip worth the money for such engine or is there cheaper alternative (piggyback computer) to change fuel and ignition timing?


Any help would be greatly appreciated

cheers
seized

Raptor

There are alternatives for piggybacks, pricing is probably much the same for all

There is Unichip
There is Xede by Chiptorque
There is Emanage by Greddy

Raptor

Forgot the other part of your question. Yes there are other options to get more from the 1.5 SOHC or DOHC. Boost will get you happening in a more satisfying way.

There are supercharger and turbo kits for your engine, go check them out.

chowetime

iTrader: (16)

there are also N/A mods that can be done as well if you have had the dohc converssion then I would be looking at better cams as there is only so much air that a car can take and use and this is where better cams come handy in being able to convert that air into something else - POWER - get some cams then go the way of boost in a supercharger or turbo but if you want to stay N/A then after cams look at T/B and you will definately be needing a piggy back GReddy E manage is what I have been using and have found it very good as most cars only need to have the air / fuel maps changed and this unit is more than enough - chips can be a bit on the limiting side for further mods

[ phreak ]

you will find that the cams on your dohc engine can only go so far and i know at the moment that Dave at RPW is working on new profiles to extrac more power out of these engines as i`m waiting to see what end result they come up with before i look any closer to my dohc 1.5

seized

thanks for replies folks!!

I may be heading 4agze sc due to low funds. Tc Automotive has qouted me 1500 large fitted w/ out intercooler. Dont know how it be reliable then, does any one know of this setup on 4g15.

Curren setup is only 2 inch cat back exhaust, air filter and Malpassi fuel regulator. Runs quiet well compared to original 4g15 sohc.

Do any of you have any problems with Malpassi fuel reg. It makes a whistling noise at startup then goes away but comes back when accellerating. What is the supposed psi setting? I am currently running a very unusual 18 psi when I thought std regulators on this car run at 3 bars (43 psi). THe more i adjust higher the whislting becomes more evident from regulator....

Any ideas folks?

cheers

guest

The noise is usually from one or more loose bolts holding the base together. Tightening them should get rid of the problem. Set it at 40-42 PSI.

-=mike=-

Mitsiman

And 18 psi is way too low - it has to run at leaast standard mitsi setting of 38 psi at idle hot otherwise you are running your car very lean.

And there are lots of nice mods - camshafts we are working on but to be honest a low priority at htis moment.

Turbo manifolds for the DOHC we are also making at this point to add them to our turbocharger range.

And don't forget the twin throttle bodies - gotta love teh way the car has a tonne of acceleration when they kick in.

Our race headers (Sigh) are supposed to be ready end of this week with a heap of other headers which are also compatible with supercharger options.

But honestly when it comes to tuning- you can't go past the greddy e-manage. Don't short cut with any other brand - this is the best and most sophisticated unit on the market at this time.

Turtle_VR4

how hard is the g-manage to tune? perth is a bit far away from me. would most local places know how to tune it?

Mitsiman

I find it very easy to tune - but then again we have had a lot of experience with it.

Most reputable aftermarket computer tuning firms shoudl have no issues tuning the software.

seized

Hey folks,

As per this thread, I have converted to 4g15 dohc 16 valve engine, and this engine came with a larger intake manifold (plenum chamber) than the original. I am looking at purchasing a larger throttle body (RPW oversized TB) but not quite sure what the std size is atm and what is the maximum oversize TB I can go for without having to have the intake polished.

I know some of you have already converted to 4g15 dohc and youll notice that the intake manifold or plenum chamber (where the TB is attached ) is significantly bigger compared to the original 4g15 SOHC's and even with the 4g93 SOHC for that matter.

Have you folks had your std throttle body replace from original 4g15 DOHC to RPW's oversized TB? (AND I dont mean from original 4g15 SOHC)

Phreak I know you had you have the same engine as me, so have you had your TB replace already or are you still running from original 4g15 DOHC TB with the larger Plenum chamber. Have you had a chance to see what the current TB sized is or anyone please?

Any advice folks?


cheers

Mitsiman

The standard SOHC throttle body is 46mm. The standard DOHC throttle body is a 50mm.

WE can machine the SOHC units out to 51mm and the DOHC units out to 54mm

ON any 4G15 vehicle a FPR unit is recomended

seized

Thanks for the reply Mitsiman, why 54 only though? or is this the maximum the 4g15 DOHC TB can be machined without compromising strength?

How about direct replacement with the ovesize 55mm as per 1.8 4g93 (only one more mm) or the oversize 58mm for Proton\hyundai as per your website?

BTW, what is a FPR unit?

Many thanks for info and apologies for ignorance
Seized

[ phreak ]

i`m still using the standard dohc tb and the fpr is a fuel pressure regulator which helps in smoothing out the flat spots that you can get with the better flow of the dohc

Mitsiman

That is all we can machine the stock throttle body out to before weakenign too much.

After this we can instead fit the 1.8 50 - 55mm unit on instead or go to a 60mm but that is starting to get very large for a small engine without sufficient mods to support it.