Help me with the engine for my Offroad Buggy!
Turbo Mini Forums

Hi guys, right, this isnt Mini based in the slightest, but i respect the amount of knowledge you guys have on here so i thought it was a better place to ask then on the offroad forums full of pikeys!

Basically, im building a winch challenge buggy, hopefully one of the most capable in the Uk, vey similar to an american rock crawler, i have attatched a picture of the insperation for it, so fairly similar to the picture.

Problem i have is with the engine. Now, with these kind of environments engines can get killed pretty quickly, so, my build is based on a Suzuki vitara engine and transmission, everything else is custom, but now im having doubts about the only vitara bit actually left!

The engines only a 1.6 , and its going to be turning 40" tyres, which i know is possible as quite alot of the rock crawlers do this, but then they arnt ploughing through mud! Most of the other challenge boys over here run either the toyota or Landrover 2.5 TD's. But, i have already got all the engine mounts, the 2 hydro pumps for the full hydraulic steerig and the winches fitted, and the engines are readily available and cheap.

So basically, at the moment its a single point injection engine, which im going to pull off and fit a carb, then fit megajolt onto that (Megasquirt is really to expensive for something like this, and its less thigns to go wrong). This way therees no dizzy to get soaking wet. Do ou think thisis worth it or should i concentrate my efforts on waterproofing the dizzy instead? The engine as standard puts out around 90hp, and i want to try and get 120+ Hp out of it. Iwas thinking about a turbo, but with offroading i really want the power to be low down and on demand when i need it. Woud a small turbo be good for this application? Should i look at supercharger instead?

The main problem i face with something like a supercharger or an NA tune, is that i will be taking a spare engine with me, and ant to be able to swap them over in a couple of hours, which is why a turbo would be briliant! Just unbolt the manifolds and engine mounts and bellhousing and swap them over.

So basically, the spec i need for the engine;
Waterproof
120+ BHP (About a 30hp gain)
Power available at lower revs (As little lag as possible)
Ideally no mods to the engine itself, maybe head work if it was needed to lower the CF and i could just swap the heads over if strictly neccaserry?

What are your thoughs on this?
Thanks for the help
Rich

The one of the left is one one im modeling off

Edited by Rich. on 9th Jun, 2010.

Have you thought about dropping your gears down? I think you can get reduction transfer case gears for sierras with something like a 60% reduction in low range. Not sure if theres something similar.

In boost we trust

Sorry, should have added that, im tunning twin transfer box's giving me 12 forward gearsa dn 3 reverse.

Rich

i would supercharge it, na tuning will move the power up the revs and reduce low down torque, turbo would bring lag
you could gear the supercharger to produce higher boost at low revs a small turbo to boost low down would be good but when you hit high revs will it be a huge restriction? probably..

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The only problem i have with a supercharger is that it wouldnt be very itnterchangeable in a hurry, unless i could make a bracket for it that bolted onto the tubework somewhere and took the feed of the already huge length of auxilary belt.
In this case what type of charger would you reccomend? The Eaton M45 or is there a more suitable one?

Thanks for the help
Rich

Surely a chevy LS2 or a vw W10 would be a wise idea?

Navara?

Yes i moved to the darkside

Instagram @jdm_brett

Awesome, that sounds perfect then!
What about lowering the CR of the engine? To get the 30 or so horsies of boost im looking for what sort of pressure do i need to be running from the charger? And would this warrent getting some headwork done?
Thanks for the help
Rich

30bhp gain on 90 is 1/3 so i would look for 1/3 bar or a
bout 5psi as a starting point
what is the std compression? Id of thlought 5 psi is doable on a stock block head pistons remember if you have the head worked on one you need it doing on the other

Yes i moved to the darkside

Instagram @jdm_brett

What are the rolling conditions ?

I don't know if it is intended to climb a hill in 1st or turn around a track at 60 mph

Because I think I would try a hi-comp / low boost in the first case and low comp / hi boost on the other.

Anyway, can a supercharged 1.6 gas engine match the low speed grunt of a turboed 2.5 diesel, I think not ...
But it is much lighter and cheaper !

Rusty by nature

I agree, its going to be a compromise, but then again i will have alot more gear options than the other competitors, therefore i can selecr my revband for a given obstcal more easily.

And yes, most of its slow speedcrawling stuff. The one thing i would say about these engines is that they like to be revved, and can quite easily rev upto 9000rpm. Maybe this is where im going wrong, i should be looking to boost higher up the revband with this engine?

Rich

I think in this kind of machines you want a low end torque. If you make a high revving engine you will loose torque.

Turbo and low end torque are not in contradiction. You just need a really small turbine and a good external wastegate, this is how WRC are made to obtain 650Nm @3000rpm with a 2L engine.
Supercharger is heavier.
The other problem is the dust, I think turbo is less sensitive to dust than a supercharger, but I may be wrong.

120hp from a jap 1.6 engine it's certainly easy. Hopefully the engine's CR is under 10:1 on Vitara, in which case you would not need to modify the engine and 7psi would be enough to get your 120hp under 6000rpm. A diesel turbo should work, like a GT15. I believe the compressor's sizes are roughly the same for petrol and diesel engines, diesel turbines are built for colder gases, so if you bolt a 1.9td turbo to a 1.6 petrol engine it should work perfectly at low revs.
If you can make an efficient cooling you can get a robust turbo engine for cheap.

Edited by alpa on 10th Jun, 2010.

std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm

Well looking at some specs it would appear the compression ratio is 8.90:1.

The dust issue shoudnt be too much of a issue as i can just stick an ar pre-cleaner onto the end of the snorkel which filters pretty mcuh everything out before it even gets to the air box.

So, im either looking for a low boost turbo or a low boost supercharger?

Whats other peoples thoughts on the GT15 or a T2 or similar? Right turbo for low range boost on this engine?

Thanks
Rich

Well apparently someones done it before!

They dropped the compression ration to 8.6:1 and ran 17.5PSI of boost and are getting 200hp out of it! Thats over double standard and about double what the 2.5td boys have, although im not sure about the torque figures mind.

http://www.cardomain.com/ride/361175

Thanks again
Rich

If you want 120 or even 160hp from a jap engine don't bother with modifying it, just bolt the turbo and it will work. I was pretty sure the CR is low, it's common on 4x4 japs.
If it's a 16v engine you'll get your 120hp at 5psi I think, you'll need say 7psi if you want high torque at 2000RPM.

std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm

That sounds perfect then!

Just one last thing, how would my standard SPI system cope with turboing the engine? Will i have to rip it out and go with carbs instead?

Thanks
Rich

You'll probably have to use something is place of SPI. Carbs + turbo is a special subject, make a search.
Megajolt is a good thing to properly tune the engine.

Note: I know nothing about this particular engine. Generally speaking jap engines are very strong and can be FI with no internal mods. Check on related forums if this engine is like that.

Edited by alpa on 11th Jun, 2010.

std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm

Thats brilliant, thanks for the help mate!

Rich

What about a basic VW tdi engine ?

They have loads of torque low down, and are ultra reliable.

Its hard to know what you need in terms of an engine given the gearing and usage.

Do you actually need a wide rpm range with all those gears ? Or just loads of torque no matter what gear you are in ? but over a smaller rpm range ?

And the diesel will be easier to waterproof.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

Well thats the thing, with the amount of gears the specifics requirements of the engine arnt quite so bad, i can just use the gears to find the power band of the engine.

Yes, the VW1.6 engines are very popular, as a company called acme make an adaptor plate for the vitara gearbox, although it does cost £500.

The problem with these engines and the Pug 1.9 engines that are commonly fitted is weight. The 1.6 engine is very light, which is briliant for me as i want to keep it as light as possible. That paired with 15" wide tyres means i can float over most things.

You are totally correct on the waterproofing issue, if i went to diesel that would be my second reason for doing so, after torque. However it is still possible to waerproof a petrol, just it obviously takes abit more work.

Rich

i have no input atall.


but do you have any more pics?
thats cool

Of my insperation Rig? I have plenty of it, its awesome isnt it!

Thats only running a little 1.3, although the tyres are 9" smaller than what im going to be running.

Id be leaning towards running it as a 1.6 with injection. More trickery and things to go wrong, but it wont die on you if it gets too angled.
You could see how it went naturally, then work on mods from there. Lightweight is the best thing for off road.

In boost we trust