Draw or blow through?
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Discussion

Liquid Knight

Original Poster:

15,754 posts

213 months

Monday 16th April 2012
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I'm planning to supercharge my Fiat Panda for this years PPC £999 Challenge at the end of June at Santa Pod.

What is the better set up blow through; like this...



...with the charger feeding the carb' or draw through; like this...



...with fuel and air being compressed into the inlet directly?

Forgive the crude MS Paintshop but you get the idea.

Liquid Knight

Original Poster:

15,754 posts

213 months

Tuesday 17th April 2012
quotequote all
Blow through would be easy to set up with a Metro turbo or Renault 5 GtT carb' with the secondary jets timed with boost, but draw through would be constant throughout the rev' range. scratchchin

stevieturbo

18,079 posts

277 months

Tuesday 17th April 2012
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A lot will depend on what carb you intend to use. As much as I'm not a fan of suck through, it would probably make more sense as carb tuning is totally normal in that you treat it as n/a, and same applies to the fuel system.

Fuel going through the rotors should help cooling them as well, almost like an intercooler effect, albeit a small one.

As I doubt you'd be trying to install an intercooler with that style of blower in a blow through anyway.

Liquid Knight

Original Poster:

15,754 posts

213 months

Tuesday 17th April 2012
quotequote all
There's not a lot of room either in the engine bay or out of the £999 budget for chargecooling. The draw through set up would be like having a solvent cooling the rotors. Also lubricating and sealing the rotors better so the charger would work more efficiently.

davepoth

29,395 posts

229 months

Tuesday 17th April 2012
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Suck through is going to be much easier - I can only think of one car with a blow through carb (MG Metro Turbo) and that needed quite a few modifications to make it work properly. Suck through works just like a normal engine. If you're using a brake servo it needs to be plumbed upstream of the charger otherwise it won't make vacuum properly.

The Eaton chargers are quite happy with fuel running through them (the kits you can buy for the MG from Moss Europe do that) and also you'll make more noise with the carb on the end rather than in the middle. biggrin

stevieturbo

18,079 posts

277 months

Tuesday 17th April 2012
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Although IMO a turbo setup would be cheaper, easier and make more power.

Huff

3,424 posts

221 months

Tuesday 17th April 2012
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David Vizard discusses the pros/cons in his excellent 'Tuning the A-series' book - I suggest it only because the scale & likely gains are similar, and it'll be available via your local library if you don't already own a copy!

Liquid Knight

Original Poster:

15,754 posts

213 months

Wednesday 18th April 2012
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stevieturbo said:
Although IMO a turbo setup would be cheaper, easier and make more power.
I've had an Uno Turbo and a Delta Hf powered Panda before I don't like the all or nothing nature of tuned turbo engines. As for being cheaper, I paid £87 for the supercharger...

http://www.ebay.co.uk/itm/130659311558?ssPageName=...

...a turbo engine swap is a lot better than fitting a turbo to an N/A engine. Then you have a complete loom and all the plumbing. Fitting a turbo to an N/A car even with an off the shelf kit can be problematic and eat budget. Delta Hf and Uno Turbo prices are sky high because they're classics now (it would be sacrilege) Punto GT donors are donors because they're jeffed, the 16V Turbo Fiat Coupe could fit but if one's good enough to be a donor it's good enough to keep on the road. 1.4 twin air and Panda 100hp donors aren't cheap enough yet. So potential donors are either too expensive, too much work (to get done by June at least) or knackered.

I've never heard of there being a supercharged Panda so it has to be done. wink

stevieturbo

18,079 posts

277 months

Wednesday 18th April 2012
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Liquid Knight said:
I've had an Uno Turbo and a Delta Hf powered Panda before I don't like the all or nothing nature of tuned turbo engines. As for being cheaper, I paid £87 for the supercharger...

http://www.ebay.co.uk/itm/130659311558?ssPageName=...

...a turbo engine swap is a lot better than fitting a turbo to an N/A engine. Then you have a complete loom and all the plumbing. Fitting a turbo to an N/A car even with an off the shelf kit can be problematic and eat budget. Delta Hf and Uno Turbo prices are sky high because they're classics now (it would be sacrilege) Punto GT donors are donors because they're jeffed, the 16V Turbo Fiat Coupe could fit but if one's good enough to be a donor it's good enough to keep on the road. 1.4 twin air and Panda 100hp donors aren't cheap enough yet. So potential donors are either too expensive, too much work (to get done by June at least) or knackered.

I've never heard of there being a supercharged Panda so it has to be done. wink
All or nothing ? must be bad setups you drove. And for a drag strip, especially on a budget power is king. You dont need low rpm torque, nor do you want low power.

As for a complete wiring loom ? From the look of things you're talking about a carburettor car which will likely also use a dizzy. Hardly much wiring involved.

Fabricating an exhaust manifold is a doddle and can cost next to nothing with scrap metal compared to blower brackets and pulleys.

How exactly does the budget aspect work ? Would be kind of hard to prove what was spent etc ?

Liquid Knight

Original Poster:

15,754 posts

213 months

Wednesday 18th April 2012
quotequote all
This is a topic of discussion. You have £999 to buy or build a car for the event both on the drag strip and a small handling course. You can sell up to £250 worth of parts to help fund the project. While it isn't strict having a build thread on the PPC forum helps. In the end you are only cheating yourself and we're a nice bunch of guys in sheds doing the best they can with the limited budget we have. Basically what motorsport should be about. Having fun and making friends. It's a really great day however well you do and you get a trackday toy as well.

Harnesses and other safety gear isn't included in the budget so it's healthy and safe.

You just need to have spent £999 and have an M.O.T to qualify.

You're more than welcome to come along if you like. smile

carlt5

41 posts

207 months

Saturday 21st April 2012
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davepoth said:
The Eaton chargers are quite happy with fuel running through thembiggrin
not what i've read with the coated roters
and there are a few coming up on ebay with the coating flaking off

not a problem in this application though !

Liquid Knight

Original Poster:

15,754 posts

213 months

Saturday 21st April 2012
quotequote all
I was thinking about the rotors before and I was thinking or treating it as I would a highly tuned rotary engine and have a bit of two stroke oil in the mix.

I got some good news today the block I have and head I have chosen are compatible. Now I just need to get the cam' and carb' and fabricate the manifolds and linkages.

stevieturbo

18,079 posts

277 months

Saturday 21st April 2012
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Liquid Knight said:
This is a topic of discussion. You have £999 to buy or build a car for the event both on the drag strip and a small handling course. You can sell up to £250 worth of parts to help fund the project. While it isn't strict having a build thread on the PPC forum helps. In the end you are only cheating yourself and we're a nice bunch of guys in sheds doing the best they can with the limited budget we have. Basically what motorsport should be about. Having fun and making friends. It's a really great day however well you do and you get a trackday toy as well.

Harnesses and other safety gear isn't included in the budget so it's healthy and safe.

You just need to have spent £999 and have an M.O.T to qualify.

You're more than welcome to come along if you like. smile
The trip to Santa Pod alone for a weekend would cost me a fair chunk of that budget ! lol

The idea of it is great, and does inspire creative thinking. But say for someone with a huge array of parts lying about they could use, a full workshop behind them etc etc, vs a guy starting with very little. The actual budget required and spent can get quite blurred.

Liquid Knight

Original Poster:

15,754 posts

213 months

Sunday 22nd April 2012
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That's sometimes the best thing about it. We get semi-professional builds and I think the more the merrier because there's nothing better than beating the big boys as well. wink

Last years winner was a Mk2 MR2 with a Camry V6 made in a shed. Superb car and bloody nice chap as well.

http://www.ppcmag.co.uk/forum/viewtopic.php?f=7&am...

I'm thinking a blow through turbo set up would be better than a draw through supercharger. The charger I've got was originally designed for a 2.3 Merc' so it'll be a bit much for a 1368cc Fiat. frown

If I can sell it for enough to buy the turbo bits I'll need the it should work out in the end. wink

stevieturbo

18,079 posts

277 months

Sunday 22nd April 2012
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The difficulty with the blower will be fabricating the brackets to mount it, ensuring alignment is perfect and then sourcing pulleys to give a sensible amount of boost. I wouldnt be overly concerned about the size of the unit in terms of airflow. It'll just have more power potential.

If there is scope for chopping the pistons down a bit to reduce the CR, go for it. If need be a very cheap and effective water injection system can be employed to stave off detonation.

A turbo just offers more flexibility. Try and re-use the factory cast exhuast manifold adapt it to the turbo. Blow through carb with a cheap intercooler. Or again forget the IC lower the CR a bit and just use water injection. The old Metro/Maestro/Montego turbo SU's are superb carbs for boost.

But you'll get a cheap turbo easy enough whether from a diesel or other vehicle.
Assuming an old engine with a dizzy, just weld up the advance weights so it limits advance which works fine but a little crude for timing ( either SC or turbo )

stevieturbo

18,079 posts

277 months

Sunday 22nd April 2012
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What sort of times did the Camry run ?

The other option is to hunt down a sub £1000 performance car and just use it.

You will pick up some nippy cars for less than £1k. Subaru's are out there, Lexus Soarer V8 or maybe a turbo 2.5 ( turbo's seem more popular though )

I know a guy who recently bought a Soarer for under £700 as he just wanted the engine, but got a complete running car.

Liquid Knight

Original Poster:

15,754 posts

213 months

Sunday 22nd April 2012
quotequote all
There's a buy or build debate every year and so far builds have won three and buys have won twice.

http://www.ppcmag.co.uk/999-challenge.html

If I could afford to spend £999 at once I'd consider it but a few years ago (when I had a much better job) I bought an Uno Stage Rally car for £999 and didn't use it because there was nothing for me to do. If I had bought the Uno closer to the event it would have been a top five car. As it was I bought a BMW 320, stripped it out and came midfield but had so much more fun in the process it was worth while.