TeamSwift

I have a quick question for the G10 gurus out there.

I have a set of 75mm Vitara pistons that I would like to install in a G10 block. Will I have to cut any recesses in the pistons to provide clearance for the valves?

Just in case you are going to send me to the search function: Don't bother. I have spent hours trying to find the answer to this specific question. Lots of mention of Vitara pistons, nothing about if they fit, besides having to bore the block to 75mm.

Thanks for your help.

They will fit, no need to mess with cutouts. your engine will simply become an interference one now.

Are you sure?

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Contact 3tech: g10pro@rocketmail.com

what g10 head are you using?... mk1 head with 2v vitara cut outs are the same as the mk1 pistons anyway... i have done this.

mk2 head?... not sure. valve reliefs are in a different spot all together.

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Tim
MT Motorsport
www.mtmotorsport.ca

Mk1 3cyl - 185whp/150ftlbs - 1/4mile 13.97@103mph

I always see people writing about mk1, mk2, mk3 etc. heads. However I have yet to find a post that shows pictures of what is actually a mk1, mk2 etc head. So I will assume that the mk1 head is the big one with the dome combustion chamber and the rocker arms. I'll also assume that the mk2 head is the one with the very small cam cover, cam running right on top of the buckets pushing the valves around, and a wedge shaped chamber. Then there is another similar cam cover that has an extra rectangular block on top, presumably for oil separation since this is where the breather tube is located.

All of this is pretty dangerous because assuming can make an "ass u & me".

My head is the second described. Simple straight up and down valves, pushed directly by the cam. No rocker arms.

If you gents have a post where the head types are clearly illustrated I would educate myself promptly.

Thank you for you help

ur right. mk1 is the only rocker style 3 cylinder... mk2,3,4,5 3 cylinders are all the same like yours...

in that case... the valve reliefs arent in the same place as the vitara pistons. what you should dooo... is get yourself a mk1 cylinder head... they have way more potential as the design is actually much better for making power... plus... the vitara pistons are then for sure drop in.

one other thing to consider though... if your using a stock NA g10 block it has the lighter duty con rods... big deal is they have a push in piston pin... the vitara pistons require the turbo or gt rods as they have a floating pin.

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Tim
MT Motorsport
www.mtmotorsport.ca

Mk1 3cyl - 185whp/150ftlbs - 1/4mile 13.97@103mph

Going to the mk1 head is one thing I want to avoid. My application is very weight sensitive, and the mk1 head is 14 lbs heavier than the later heads. I don't really need the extra power either.

These pistons have a treatment on them that should make them more reliable. My interest is purely in reliability.

I have heard nothing but good things about the rods so I was hoping to be able to keep the NA ones I have. That brings up another question. What is the press fit in? The piston or the rod? From your comment I surmise that the pin floats in the rod and is press fit in the piston.

Does Jardamuth's comment regarding an interference engine still hold true? I don't mind an interference engine. If the belt breaks the result is a dead engine no matter what. In this case some extra engine damage.

Thank you for your info.

somebody is making an ultralight...

the vitara piston uses a 19mm pin, the NA G10 (press fit pin) is 17mm. there is not enough material in the NA rod to bore it out to 19mm. you could get bushings made for the pistons to bush the 19mm hole down to 17mm...

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Matt
Megasquirt Specialist.

www.mtmotorsport.ca

No bloody way on the ultralight idea. I intend to go three times that fast.

Now I have to go look for GTi rods or turbo rods then. Maybe I'll just go back to stock pistons.

Cheers

haha


the turbo/GT rods are much stronger than the NA rods, but are heavier...

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Matt
Megasquirt Specialist.

www.mtmotorsport.ca

OK Gents,

Its been a while but I have been picking away at my little engine project. Another question about the interference of the valves and Vitara pistons. Do the lifters compress when turning the cam on the bench? I turned the cam over with one of the pistons at TDC and no interference at all. Have not done the clay on the piston crown trick yet to measure how much clearance there is though.

Second pic is the piston rod combo in the engine. Top is original, bottom GTi rod and Vitara piston.
Third pic is the head mounted on the jig for drilling the injector bosses.

Cheers,

A little while?
It's been 3 years

You shouldn't have any problems with it being interference.

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Contact 3tech: g10pro@rocketmail.com

That's because my daughter is now three years old, have a new job, live in a new city, and finally have time to get back to my project! At least nobody can accuse me of not having patience. Thx for the info.

Also: what about the brand new lifters I put in? Do they need to be pre-charged with oil? Nothing in my manual regarding that. Although it does say to keep the removed lifters submerged. I submerged the new lifters, but no air bubbled out of them, so I doubt they filled up. I just hit the old lifters "with anger" on a piece of wood (a la Caarlo) and they came apart just fine. And I'm not even really angry.

Early July I'll be able to get to my second engine so I can send you that cam-core.

Cheers

_________________
Contact 3tech: g10pro@rocketmail.com

Absolutely

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Jardamuth,

I have no reason to doubt you. You seem to have a lot of knowledge on the topic and these engines in general. For the moment the engine is mostly together and not an interference engine yet. This may change with oil pressure in the lifters. I have not measured and compared the valve lift at the valve face to the lobe height. I'll do that and let you guys know.

Cheers and thank you for all the info. I'll be back for more.

With a 89+ head, how can it possibly be interference?

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Contact 3tech: g10pro@rocketmail.com

im planing on doing my treebanger turbo is an mk1...can i use the gti rods with the stock piston head???
thanks for your help

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suzuki forsa 1985 (SA310)
g13bb swap
GTi flywheel
clutchnet 3 solid puck clutch
clutchnet red pressure plate
honda short shifter> back to stock shifter
short ram intake
baleno 1.6 ecu
custom header with 2" exhaust
GTi front hub and calipers swap
soon mk1 GTi exterior coversion

nice thread here, i would want to hear a follow up on your project. ..
cheers

Dear Turbo Gurus;

Here is a pic of my exhaust manifold. It is made out of 321SS 1.5" tubing. All the turns are mandrel bent. The distances from the head to the turbine intake are #1=19", #2=16.5", and #3=15" (I know not perfect but I'm limited by packaging requirements) The down-pipe from the turbo is 1.75" and 19" long. No muffler. I'm not interested in turbo-lag. This engine will be running at a constant RPM from the high 4000 to the mid 5000, and at 12,000 feet. I plan on running stock 7.5 psi boost. The turbo is a RHF4. The engine will be managed by a SDS fuel/ignition system.
The question is: Roughly what kind of horsepower can I expect? (I'm just looking for some realistic estimates, not a bunch of wild out of the ballpark guesses.)

Thx guys.

Taking all the fun out of it eh...

What cam, compression, and intake are you running?

All your gonna get without the right info is gonna be a bunch of wild out of the ballpark guesses


Scott

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Its not lag, its suspense...
1987 mk1 T3

You're absolutely right.

Stock cam
Stock valves
Head was taken down 0.010" to make sure it was true
Ports are stock, but given a good sanding to smooth out.
Swirl jets are gone
Fuel injected
75mm Vitara pistons on GTi rods (see pic in earlier post) I have not worked out the exact CR
I'm still working on the intake manifold, but it will be a simple plenum, about 1 litre displacement, made out of 3" tubing, with roughly 6" long runners to the valve face. (Don't really care about low end torque)
Intercooler from a Mitsubishi Eclipse.

What did I miss?

@7.5 psi boost and proper fuel delivery you'll get about 100hp. you'll have to correct for barometric pressure at altitude. no bashing, but the log style manifold is the weak point but i understand your need for the "package."

you should be pretty safe with the g10 as they're nearly bullet proof. my dad and i built several planes powered by g10s. he had a rotax go tits up on him in flight but never a g10.

the last plane he did was an enclosed trike and we had all kinds of "package" problems, even with a fairly compact fmc engine.

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Thank you. No bashing taken . I know the manifold is not optimal, but I did the best I could with the space available. From other aspects you can see that it is not a true log and that the flow is not that bad either: