Hello All. I live in Bangkok, Thailand (originally from Chi-town) and own a JDM Evo VII that's all stock except for a cat back, adj. cam gears, and a tune. Was pretty much gonna leave it at that, since all I wanted was a fun daily driver, but I blew a piston. Damage is a blown number 2 piston, scuffs on the side of the number 3, and some scratches on both cylinder walls. There is no damage to the con rods.

Because of all this, I'm gonna:
a) bore out the block and upgrade the stock pistons to 86mm
b) replace the main bearing and the con rod bearing
c) upgrade the cams for higher lift and duration (maybe JUN 272, 10.8" lift)
d) up the boost and tune on a dyno

I'm not lookin to upgrade the springs, fuel pump, or injectors at this time if i don't really have to. Money is a factor in all the decisions, and i'm lookin to get the right combinaton of mods for the money to reach my goals.

My goals:
a) increase and improve the low and mid range torque curve
b) up the hp a bit (right now it's around 290)
c) above all, maintain reliability and smooth drivability (Bangkok traffic
is a beeyatch)

My question is this... Do you think the mods are appropriate in relation to my goals? Suggestions? Just lookin for some feedback and/or constructive input.

Sorry this first post got so long. Much thanks for all replies in advance.

 

i had the same problem on my evo VII and i had to do this:

new oil pump
new water pump
ARP head studs
A combo of JE forged piston and manley H Beam Rods
Cosworth gasket
Valve Stem Seals
Balance Shaft Eliminator Kit
Greddy Extreme Kevlar Timing Belt
oil filter

Hey are you on the second super ok the block? Why are you going to 86mm?
try to go 85.5mm so you can have an extra super for your block!

Goog luck

 

i forgot ,
Cosworth EVOVII-VIII Rod Bearings
Spark Plugs
and new oil change try liqui moly

look at the "I NEED A TURBO" topic in this same page , there are some pics of my building

 

any updates?

 

i dont know about the VII but the VIII here state side needs a new fuel pump at around 320hp so you will want a walbro 255 with the jun cams. while you are at it larger injectors would be beneficial to you as well

 

Not addressing the fuel system while building up the engine is not going to do much for you powerwise, especially if you plan to increase the boost. You're obviously looking to make more power, but in order to do that, you are going to have to add more fuel. That being said, you have options depending on what you want to do.

In whatever you do, you're going to at least need upgrade your fuel pump. It's not really up to the task of keeping up with increased fuel demands.
Next up, do you plan on running any sort of engine management, to include an ECU flash? If you want to maximize your your potential gains from the cams and increased boost, you will want to plan for this.
Finally, have you thought out a desired horsepower output? If so, have you done the math to see that you have enough injector space for your goal or will you need bigger injectors? If you're not looking to make substantial gains, then you'll probably be fine with the stock injectors. On RC Engineering's website, they have an injector/horsepower calculator that can do the math for you to look it up.

 

nice webpage !!

thanks

 

I will be replacing the fuel pump. I must have typed it in by accident when my train of thought was on fuel delivery. I am trying to get away with not replacing the injectors, though, due to overall mod cost. As long as I can reach my goals, I'm not really lookin to change too much more. Unless its a super bang-for-the-buck mod.

The engine runs on a Motec M400. Sorry; forgot to mention that.
For up to how much hp will the stock injectors be sufficient?

While I do want gains in hp, I have no targeted number. I am not even sure what kind of hp and tq numbers to expect after these mods. I know it will depend on alot of variables, but any ideas? Ballpark, I mean.

I am more interested overall in low to mid range torque. Since this is my daily driver, I would like it to be more responsive before it hits boost and a bit after.

Kemoly typed: Hey are you on the second super ok the block? Why are you going to 86mm? try to go 85.5mm so you can have an extra super for your block!

I'm not sure what you are asking. What is "the second super", "extra super"?
At least 85.5mm pistons was the original thought, but that was just to get past the damage to the cylinder walls. But since we have the chance to change the pistons like this, we decided on 86mm.

Updates might be a bit late. Profile still says I'm in the Chi, but I'm in Thailand (12 hr time diff).

 

sounds good, hope to see the progress

 

You might want to look hard at why you blow a piston and do you really need to run that Motec? Maybe sell it, install a stock ECU and spend the money on brake up grades. New rods would be a good idea if not already planned.

MB

 

From what I remember, stock rods are good to around 500+ hp. Am I mistaken?
Another concern is speed. Will Stock rods hold up to 200+ kmh?

 

Most people in the UK would say the VII rods are only good to 400Bhp. Speed isn't really an issue with rods, it's more RPM and tourque. My car has been held at 250 Kph for over 4 minuits on a banked cuircit, and been on the Nurbergring and Spa at in excess of 200 Kph.

Again you have to ask why your piston failed? Knock is the usual problem, but also running lean can do this, the pistons are able to handle more power than the rods. Additionaly if you have had a piston fail, there is a high chance that your rods have been stressed, so replacing the rods is really the only option, fitting rods and pistons from a IX could be a good low cost path as these are thought to be stronger.


MB

 

BKK VII, got any pictures?

 

^^ what he said

 

Don't have any pics of the internals as of yet. Block's aleady at the machine shop, but I will get pics of the pistons. Goin to the garage this weekend to settle some details. Will also try and hash out the details how the piston blew.

In regards to the rods and pistons from a IX... My block needs to be bored out to at least 85.5 mm. I was most likely going to go to 86mm. To the best of my limited knowledge, the IX has ~85mm bore x ~88mm stroke, the same as a stock VII's. If I am wrong, would stock IX pistons and rods fit my VII's motor after its bored? I will look up the specs, but does anyone know offhand? Up to how many horses are they supposed to be good? I have no specific hp targeted, but i'm lookin to get between 350~375 hp, not with these mods only, but eventually.