To all Pressure charging experts,

I'm thinking of supercharging my Mk3 GT, but dont want a g40 engine, so if i buy a Charger from Jabbasport, do i need to uprate my pistons n Conrods n such??! :) to anyone who knows the answer, FAIR PLAY!! x

Stock internals should be fine for a bit of boost but you need to drop the pressure down or have a way of controlling it, most stock engines N/A can handle about 6psi safely but I know that a 1.3 AAV engine can run 1bar quite happily, not too sure how this would effect the GT with its higher compression ratio ddo.

still only way to find out is to try it :)

Ill just leave this here....

And they said it couldnt be done....

Edited 2 November, 201015 yr by Cymro

Ahhh, the old HTT boosted polo. How did he get round the carb+boost issue?

Ahhh, the old HTT boosted polo. How did he get round the carb+boost issue?

I would imagine he used a blow through carb.

BTW Abd engine are much better for turbo or supercharging as they have much lower compression ratio, and you can buy an abd lump for cheap

http://www.polog40.co.uk/forum/index.php/topic,3687.0.html

Heres a link to a thread on the g40 forum, some bloke got 176bhp from an Abd lump using standard internals.

yet to see any of these actually still on the road for more than about 4 months though

yet to see any of these actually still on the road for more than about 4 months though

Did Tommo's go pop?

well, last I heard he was running it without the turbo on for whatever reason and then he just disappeared. What he did was impressive and he got good results but it was only a cheap solution for him because he had access to and knew how to use lathes, milling machines, decent welder etc... so I'm not trying to bad-mouth what he did but I dont think the car lasted very long for whatever reasons

The one pictured above ran for a while i think. Was on the forums for as loong as i was using it

But it wasn't running the 'charger plumbed in. There were pics from it at a show where he had the Eaton spinning round, but it wasn't boosting the engine...

Throwing something together and taking pics isn't my idea of getting something working. Tommo deserves credit for his budget ABD turbo - but I think he recognised it probably wouldn't last for 20,000 miles without needing a rebuild.

To be fair, if you don't want to buy a G40 engine, and can only stretch to the G40 supercharger I'd suggest selling your GT lump and buying an AAV or NZ as they're slightly lower compression - and so cheap they're practically free. Only thing to bare in mind is how you're going to fuel the thing - you'll need to buy G40 injection, or look at carbs capable of taking boost. Both the budget boost conversions mentioned in this thread used R5 turbo carbs.

Stock internals should be fine for a bit of boost but you need to drop the pressure down or have a way of controlling it, most stock engines N/A can handle about 6psi safely but I know that a 1.3 AAV engine can run 1bar quite happily, not too sure how this would effect the GT with its higher compression ratio ddo.

still only way to find out is to try it :)

Ill just leave this here....

And they said it couldnt be done....

Cheers man!!!! and is that a Twin Screw charger?? looks fat lmao

Eaton aint it?

I see no logic in using the GT engine, the high CR means you are very limited to how much boost/timing you can run.

As for my car, it didnt die as such. I did about 9000 miles in it, and all was fine, but then the actuator pipe blew off whilst I was ragging it and it ran an unregulated amount of boost for a short time, which popped the head gasket. It was my own fault as I never had any clips on the pipes.

Anyway I replaced the HG, but I got new bolts from GSF in huddersfield and I fell for it for the second time! Wrong bolts, too short, so one stripped the thread in the block when I torqued it up, so I fitted a longer bolt and just tightened it as much as I dared. So as you can imagine I was pretty pissed off, and feared that it would cause the HG to blow again, which I didnt want.

Also I didnt want to change the oil (as it had a lot of water in the oil) until I had run it for a bit to check the ring lands werent damaged (no point spending £12 on oil if the pistons are knackered). So of course I got it running at about midnight on a friday night, went out for a quick blast, which quickly turned into a massive midnight moorland ragging sesh. Next thing the turbo starts making more noise than usual, water in the oil had shafted it.

So I scrounged about and found enough bits to repair the turbo, (I think I did run it N/A for a period, just with a blanking plug in the turbine housing instead of a turbo lol), and changed the oil. By this time I was just shoving any old shit on to get it going to go out for a bit of a rag, as I didnt want to spend any money on a car with a stripped thread in the block.

Then I think the insurance or tax ran out or something, and I had two other cars on the road at the time, so I wasnt going to renew it.

Next thing we got giddy tuning my mates land rover, so we took the turbo off the polo and it went on that, then my other mate wanted a cylinder head, so he had that off it. Then it sat around for a bit before I weighed the car in. I kept all the bits that cost me money, the intercooler, carb, wideband etc.

But it was for the best for sure, it was just stopping me from cracking on with newer projects. I only built it to see what would happen, just as a bit of an experiment, and I enjoyed building it and learning all the stuff I learned from doing it.

I have no idea how anyone can say that it is less likely to last as long as a G40 type turbo setup would. Sure the rods were a bit weaker on the ABD but they withstood enough abuse to prove themselves up to the job. If anything I think my car would have lasted longer as I never revved it past 6800 unlike a lot of these other setups that rev over 7000. The pistons wouldnt withstand as much detonation as forged ones but if there is no detonation then there is no problem. Bear in mind that a turbo car is under minimal stress when you arent loading it up too, and how often could you utilise 200+bhp in a polo? Not long enough to wear it out in a short amount of time thats for sure. My car withstood many miles up the motorway at silly speeds, but you were only ever flat down on the throttle for 10/15 seconds at a time, anything more than that and you were going way faster than a polo should ever go. I had the speedo all the way around and pointing at the floor, and even then I bottled it before the car ran out of go (although my speedo did only go to 120mph).

The only thing that might have killed my car prematurely was bore wash, as I ran it rich (only because I couldnt be arsed changing the jets). But there was no sign of any excessive bore wear in the 9000 miles that I did.

I dont see what you have to do to prove to people that there is no point spending silly money on forged pistons etc if you are only after 50bhp per cylinder. Especially when VW made a perfectly good stroker kit that you can get out of a golf for next to no money.

Oh and IIRC an ABD is the same compression raio as a normal polo 1.3, 9.5:1. Mine was only lower because I skimmed the pistons.

Anyway, I hope this post clears up any speculation about my car not surviving very long. I know there are people that have spent a lot of money that would like to believe that it exploded the day after it went on the dyno. But seriosly anyone who thinks a G40 engine with forged pistons and a big valve head would last any longer running the same power is delusional, same main bearings, same big end bearings, same block near enough.

Personally I would have liked to see it explode, it would have been a nice end to the project and I would have some nice pictures and a tale to tell. Also I could prove the polo engines weakest link and then there would be factual evidence that people could use to strengthen their engines where it is really needed, instead of working off hearsay and being sold stuff they dont need by tuning companys that want to shift stock.

I think now we are only left with Yoof to really test the polo engine, his car should make silly power with the new turbo on, I wouldnt be surprised if it was 240bhp plus. Then he wants to get some rods made to connect his big bore forged pistons to an ABD crank, so he can go 1500cc. Just my opinion, but someone needs to do it!

Edited 25 November, 201015 yr by Tommo32

Tommo.. ill be honest, i didnt expect it to last lol!

Especially as you practically did just throw it together to see what happened haha!

Standing next to it at the RR was bloody scary in all honesty. i was expecting it to explode and shoot pistons and rods all over the place lmao.

I'm also surprised that after the results you got at the RR day, nobody else has even attempted to do the same

I may have to give it a go at some point, maybe next summer even. As from what you said before, it didn't cost you a great deal to put together?

Standing next to it at the RR was bloody scary in all honesty. i was expecting it to explode and shoot pistons and rods all over the place lmao.

You should'a sat next to him in the driving seat!!!

haha!

This has got me looking at bits to to start collecting now lmao!

It was a Renault 5 turbo carb that was used wasn't it? standard one?

haha!

This has got me looking at bits to to start collecting now lmao!

It was a Renault 5 turbo carb that was used wasn't it? standard one?

With all due respect, unless you've got the equiptment/skill that Tom has when building his, you'd rack up a fair old bill at any machine shop, which then you'd start to question the budget build route.

I'm of the opinion that the ABD isn't as strong as the G40 engine, the Germans have proved this with both the 1.6 and 1.4. As Tom correctly says if you're using it as a road car, and not on boost all the time, it probably will last, if you're thinking of a trackday toy, or any race series, then non of the Germans bother. I also know that at 220bhp you've found the 'hard limit' of the later small blocks. The G40 bottom end I'm led to believe is good for circa 300bhp- I've got no evidence to prove this personally though (not yet).

I think what Tom has shown on his ABD motor, is that unless you're reaching for the sky with power, they'll suffice (providing attention is paid to the necessary areas he's highlighted, namely fueling and ignition), this is obviously dependant on your ability and skill with various machine tools, and general knowledge of engines, clearly in Tom's case it hasn't been a problem.

The case for a G40 turbo is still a strong one, buy an engine off the shelf, buy a turbo kit off the shelf, buy a map off the shelf. Bolt together, and job done, all bolt on parts, with spares available and mountains of knowledge from people already running the same setup. It's a well trodden path which you can quantify results before building the engine almost.

That said, I'm all for doing things against the grain, hence a 200bhp+ shopping trolley :-D

Tom.

What kind of MPG were you getting from that polo?

If I'm honest, I was half expecting it to blow up too! I set out with the intention of finding the limit of something, but nothing would give way. The only time I prayed like hell it wouldnt blow up was on the dyno day, as I knew if it shit its self on the dyno I would never live it down, hence I felt like I had tuned it pretty safely really, and as a result I didnt expect the figures that it made. But once it has held the power a few times you know its going to last, its not like a high revving high compression engine that is highly strung at all times.

Yoof is spot on with his comments I feel. In a serious racing scenario the whole game changes. As everyone knows, road cars and drag cars have a very easy engine life, thats why there are people building 1500/2000bhp wanky pushrod turbo V8's. You don't load them up for more than a few seconds at a time, a track car however sees constant punishment for sometimes hours. Yoof is also right about having a knowlege of engines and whats actually going on, you need it. Read books, talk to people who know what they are doing. Dont just copy what everyone else is doing.

There was definitly some timing left in my car and a little more boost, but by that time I was actually pretty fond of the thing, so I didnt really want to push it much harder. With a few tweaks and a couple of dyno pulls, and a pinch of good luck, it would have probably seen 220bhp before the wanky carb proved too much of a restriction.

The carb was R5 turbo. I used a metro turbo fuel pressure regulator because you could adjust it. The R5 carb seems best at about 6psi + boost pressure. If I'm honest though it was merely a convinience choice as I had it knocking around, the R5 carb only has a 25mm choke (compared to a G40's 46mm or whatever it is) so it is a pretty major restriction. A metro turbo SU would probably be a better option but I just hate SU's, I think they are 1 3/4".

My car did about 25mpg, a bit less if you ragged it. Which I thought was absolutely abismal. It fuelled pretty poorly off boost and I was on a max of 18 degrees of timing so it was always going to be bad, although I fitted vac advance later on which helped.

If anyone seriously wants to have a crack at making a lot of power, then use the MPi inlet manifold etc and run megasquirt or whatever, learn how to map it yourself. Then just get some G40 pistons to lower the compression ratio on a normal 1.3 engine, look up how to size your turbo correctly, fit a descent turbo and start upping the boost.

It might not have looked like it but a lot of time went into my car, not just building it but setting it up, tweaking it etc etc.

The turbo'd ABD was proof that budget builds work if you know what you're doing and have the right tools at your disposal. It'd have been interesting to see what'd have happened with the motor long-term if you'd pushed the timing a bit further and sorted the fuelling for better economy.

I know there's an AAV turbo being built at the moment that'll run G40 management. I reckon it'll work very well, but I don't think it'd take 22psi of boost plus nitrous that a G40 lump with forged pistons can accomodate.

Fair point on the skill and knowledge. I'll admit, i don't have a great deal of it haha! However, I'm always wanting to learn.

I don't know why i didn't think of the possibility of using a SU carb. Afterall, its what a lot of supercharged/turbo'd minis use. Also, Max has made a inlet adapter thing to mount one onto a standard inlet (1.3 spi one i think) So that does kinda make sense.

HIF 38/44 carb could also be used as i think its the 44 that comes in the 'off the shelf' supercharger kits for the a-series.

Machining shouldn't be too much of a problem, i know a few people

Probably still will have a blast at it. Its what i normally do, just go at it and figure it out as i go. Worked so far with everything else I've done to the car lol.

Have you seen PVW and Golf+ this month, and the turbo charged K70? It uses a suck through method, where the turbo doesn't blow through the carb, but suck an air and fuel mixture through. I considered this a while back, but was a little inexperienced, and not sure which super charger (as that was the plan at the time) to use. It eliminates the need for a sealed carb, so could be easier to put together

Anyone with ideas?

Now you have said that, my above comment about SU's and HIF's fails. As it made me think of how a supercharged a-series bay looks.

The carb is moved to the top right corner (on most) therefore it must be the same as above. Carb then supercharger.

Found a pic

Edited 28 November, 201015 yr by B-shaw

I thought the su utilised a suck through method. Problem with this is the inability to use an intercooler And the height issue with trying to mount an air filter on top of a carb on top of a supercharger on top of the inlet

Have you got any more pics of the above mini?

Edited 28 November, 201015 yr by prankstar2003

Suck through is a bit gash IMHO. If you are going to the effort of converting your car to forced induction then it should make good power otherwise its a waste of time, and suck through is just too limited for that I feel. OK for china-tastic off the shelf kits that are just made as a quick easy power adder, but not a serious tuning modification. Then again I have never messed with blow through setups, but its probably like anything else I suppose, you can get a lot more power out of them than people say if you are careful and act wisely. Heavy use of water/methanol injection would probably see it right, but it would probably end up using more water than fuel.

Also, many people call my car a 'budget build' which is fair enough, but I wasnt ever out to compromise my car to keep costs down. Most of the stuff I used came from production cars, not just because its cheap and readily available, but because the quality of it is 10x that of almost anything you can buy aftermarket. Cosworth 4wd intercooler for example, does 220bhp no sweat on a cossie, more robust and better made than any aftermarket intercooler, got ends that you can weld into whatever configuration you want, all for £20 off ebay.