Engine Rebuild (update march)

well iv decided to rebuild my engine and after looking at alot of threads on redline with the turbo gtis i dont no which way to turn.

its either standard rebuild with +.25 or +.5 pistons (£220ish)

or

vitara pistons,
then its either nippon or ycp(ebay usa), either 75mm,75.5mm or 76mm (£120)

i aint lookin to go turbo straight away, realistic the summer or next year, but i dont use my swift much as i use my van to put milage on.

i know running vitara pistons will lower comp and without turbo will b less bhp than standard but would the bigger pistons make up for the lack of compression...?? to get the same/ similar bhp na

i seen ricardo on redline ran his for a while and he sed about -10 to 12bhp.....
just want some ideas and knowledge b4 i go any further

and i dont have a money tree in my back garden so its only getting rebuilt once

Thanks
Ross

if your only rebuilding once and you plan to go turbo in the future then you have answered your own question. It will be a bit sluggish with the low comp pistons and no the the extra displacement will not make up for it, but at least you can get the engine nice and run in before fitting the turbo.

well i say only once id run low boost then if i wanted high boost in the distant future id have to change parts anyway, just dont have that kind of cash lying around atm.
the turbo in the summer would only b a low boost setup and probably a cheap 1 at that.

ps. happy birthday stevie btw


Ross

You could go high comp low boost?

I got most of my parts from suzuki.

Pistons were 150 ish quid.
Gaskets were loads, and they had supplied me with wrong oil pump seal which was ALMOST correct

Rings get from john foreign engines. same with bearings. although if i were to rebuild engine again i would try to get suzuki bearings (colour coded)

thats sort of what i was getting at low compression low boost
or higher compression low boost?
if the low compression could be turned up slightly more and have longer engine live then its worth it.

Hi,

If you go with Vitara pistons, you will need to have re-bored.
Why don't you get your engine block milled so that you get 8.5:1 CR rather than 7.8: or so with straight re-bore/overbore.
Std G13B has 10:1, so by skimming from the block will increase your CR to regain performance.

Then when you are ready, fit TD04 turbo and have higher boost.
Whatever you do, you will be looking at £500 minimum for your engine rebuild.

I will go ahead with Vitara pistons way and get o-ringed by Andy aka Garndi.

Cheers
Atchi

id need a rebore either way as its worn.
it seems a bit dodgy the block, how much would u need to take off to gain that 8:5:1 and i thought it was nearly that anyway...?
and doesnt that defeat the object of vitara pistons if u shave the block to gain compression or is it still considerably lower than standard.

i was going to use t25/t28 only cus i found a stainless manifold really cheap with that flange.

im payin sum1 to build my engine but i think im goin to buy parts as i dont no where he got his prices from lol, but about £800ish overall

Ross

Hi Ross,

If you read either Teamswift or Redline, they will tell you it is more like 7.8:1 or something like that.
I can work out what you need to machine it to get 8.5:1 but you could even go as much as 9:1 so you get best of the both NA and turbo.

I think re-bore will set you back about £80 and £20 for milling.
Pistons £120 off USA ebay(they are good for 600+ in Honda).
Vitara head gasket and G13B gasket set £50.
Bearing shell..... £150
O-ring... I don't know but ask Andy!

You could even try to get hold of +10 thou" ring set and just horn the cylinder.

Cheers
Atchi

i dont really no whay o ringing is and y i would need it?
I was going to use a mls headgasket

if u could work it out that would be great atchi, if it isnt too much trouble

re-bore £80
Pistons £120 off USA ebay(nippon or ycp whats best if any??).
mls head gasket £80
G13B gasket set £50.
Bearings £50-80
head bolts

Hi,

From doing some maths.
You will need to get 1mm or so off in order to increase 7.8: to 9:1 ish CR.
Here is how.
assuming you are having 75mm bore with 75.5 stroke.
swept volumw will be 333.4cc
Std G13B chamber volume is 32.4cc
head gasket is 1.25mm so about 5.5cc
So..... 32.4+5.5=37.9
333.4+37.9:37.9=9.8:1

But I think you will have big space above piston to be deacked. So you want increse this 9.8 figure to 10.8:1. So.... you want to take out about 3.8cc. This will be 0.7mm from head or block.

After you get back your engine block. You want to check how much space you have with Vitara setup compares to std Gti piston setup.

Above maths is only works if everything else is in same condition. Because it isn't with Vitara pistons, you get 7.8:1 with Gti head.

I hope it makes sense.
You could try this as well.

http://www.virtualengine2000.com/ProgramDownload.htm

Cheers
Atchi

most of that went way over my head lol, but ill take a look at the program and see if it makes anymore sense

Thankyou

Ross

just fit the vitara pistons and use a t28, t25 isnt good enough.

Hi Ross,

When you take engine out. Take your cylinder head off and measure how far pistons are from the deck. Then when you get block bored out. measure how far Vitara pistons are from the deck. This will tell you why CR is low. I'm guessing but it will be about 2mm lower than std Gti enigne is.

Cheers
Atchi

hi atchi

the engines already out and in pieces, a bit l8 to measure surpose i could put it bk together.

i didnt really understand ur calculation...
how does 333.4+37.9:37.9=9.8:1 ??
id want to aim for compression between 8.5:1 and 9.1

altho i think i just understood is that comp ratio worked out the second bit if i want to raise compression on vitaras from 7.8:1 to 8.8:1 it will be 0.7mm...?

i tried that engine program just dont no what cbr is?

thanks
ross

Hi Ross,

If you add 333.4+37.9=371.3 then 371.3/37.9 is 9.79 approx 9.8:1 CR.

I have spare engine I got from Allan in my garage so I will measure it tomorrow.
I think Gti engine will be either 0.5mm out or flat.
I wish I measured my Vitara psiton engine before I handed over to Allan!

I will be making my G10 engine to be turbo charged as well so I can measure than one also!

Cheers
Atchi