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Supercharging a GTA 3.2 24v motor into 116 GTV -ideas ?

Post by kevin »

As the topic suggests , would any one be able to shed any light on best supercharger to use and pulley sizes on a stock 3.2 motor . I am assuming that Sprintex be the choice .
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Re: Supercharging a GTA 3.2 24v motor into 116 GTV -ideas ?

Post by Duk »

Greg, you're up!!!! :D

Seriously though, a twin screw (Sprintex, Lysholm, Whipple) supercharger would be the go, but you could also look at the Eaton/Magnuson TVS range.

It will come down to making an accurate, solid mounting system that has the SC in correct alignment with the drive pulley.
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Re: Supercharging a GTA 3.2 24v motor into 116 GTV -ideas ?

Post by MD »

Application. Street or track?
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Re: Supercharging a GTA 3.2 24v motor into 116 GTV -ideas ?

Post by Joemart »

Hi Kev

My few cents worth (some of the knowledge I have gotten from Greg's book -thanks), although I am sure Greg will comment as well... :D

As you know, in SA we are restricted by the availability (lack of) of superchargers at reasonable prices, due to fact that we do not have many cars in SA that have had SC fitted....

So, we can probably get our hands on Eatons/ Magnuson from "old" Mercedes, but I believe they have a "clutch" mechanism that may cause problems - still trying to get my head around that one :( ......Maybe someone can guide on this one?

We may be able to get some Vortech's at reasonable prices, as there are a few guys locally that bring them in..... BUT, as per info (from Greg's book as well), there are a number of inherent challenges with these...

The other option is to try get latest Eaton/Magnuson TVS range (from US Scrapyards????? - can anyone help here????), which I have heard good reports about, BUT again, finding one or two is a challenge, PLUS cost of bringing in including TAX can possibly get exhorbitant....

So, in summary, Greg's book has a lot of detail re Pulley, sizes, Boost, etc BUT the detail is ALL dependent on the Charger being used...

Talk when I see u, but for us, it would be a case of getting help from Stateside for "recon" chargers, THEN we can really do something :wink:
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Re: Supercharging a GTA 3.2 24v motor into 116 GTV -ideas ?

Post by Duk »

MD wrote:Application. Street or track?
I'm sure Greg will remind us that the limit of the whole shooting match will be the transaxle. And with a 3.2 litre 24 valve + a supercharger of just about any type, will find that limit pretty quickly.
Joemart wrote: So, we can probably get our hands on Eatons/ Magnuson from "old" Mercedes, but I believe they have a "clutch" mechanism that may cause problems - still trying to get my head around that one :( ......Maybe someone can guide on this one?
Supercharger set ups with an electromagnetic clutch are a strange one. Toyota used that set up in the mid/late 80s. They have a poppet/plunger style bypass valve rather than the Eaton/Magnuson butterfly bypass valve.
Even when the clutch is not engaged, there is still sufficient air drawn through the SC at part throttle cruise to turn the SC rotors. About the only advantage I can see is the potential for some improved part throttle fuel economy and maybe improved SC life as the SC spends less time turning at it normal drive ratio speed.
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Re: Supercharging a GTA 3.2 24v motor into 116 GTV -ideas ?

Post by kevin »

Thanks for response guys . As joemart mentioned we are limited here in supply so trying to see if it's feasible to do all this work and achieve a good return .
I still have brand new GTA engine in a crate from Alfa . So I thought I could put this in the front mount GTV with supercharger hoping it could match the power of the 3.7 . I would keep that (3.7)as spare engine. The GTA engine cost me nothing and I don't wont to let it go to waste in storage .
Yes it purely for track use and fuel consumption is not an issue . The Standard compression of the GTA is 10.3 if you measure not 10.5 as per book . This was discovered when we were racing production cars by glenwood so they got dispensation to take a bit off the heads and still be in regs .
I don't want to pop a head gaskets so would like to keep boost lowish.
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Re: Supercharging a GTA 3.2 24v motor into 116 GTV -ideas ?

Post by MD »

Kevin,

I don't think you realise the work involved in converting this engine over to forced induction. For a start, you WILL need to take the heads off and fit head gaskets that are made for this application. I am sure it is possible to run the engine with a standard gasket but reliably for how long is anyone's guess, especially for a used engine.

I have no doubt at all that even fitting a recycled blower from a Merc. would see enough boost from 10.3 CR to put the power well past your 3.7 engine. Controlling the detonation and using the original cast pistons would always be reliabilty question.

A Roots type blower should see the engine make ridiculous power and one placed centrally in the valley is probably the first choice and one that has been very likely done by Greg many times over. All roads lead to Rome. ( or Greg in this case :) )

Given your time constraints, I would imagine you would have to farm this work out and have the finished job shipped to you in which case, it would be simpler to just take it with you and find a blower in the UK for it (or have it shipped there). I can see much swearing and anguish rushing this job otherwise.
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Re: Supercharging a GTA 3.2 24v motor into 116 GTV -ideas ?

Post by Giuliettaevo2 »

@MD;
kevin wrote:I still have brand new GTA engine in a crate from Alfa .
So it's a brand new one, not used.. :wink:

I would not be to worried about putting some boost on the stock headgaskets. 0,5 bar pressure should get the 3,2 easily over the 300 bhp mark. :D

Greg didn't have headgasket problems did he?
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Re: Supercharging a GTA 3.2 24v motor into 116 GTV -ideas ?

Post by 75evo »

Rotrex has lower discharge temps and makes the car feel for NA. The posi. disp. s/c are better but maybe the higher discharge temps.

But why do S2000s with 11:1 CR get to boost upto 10psi with no problems?

I'm thinking of boosting my 12V with 11:1 @ 5 psi with intercooling. Extra 50 bhp is all I need. :roll:
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Re: Supercharging a GTA 3.2 24v motor into 116 GTV -ideas ?

Post by Greg Gordon »

Wow, a supercharged 3.2! Yes, as predicted, I will say almost any decent supercharger will allow the 3.2 to make enough power to break the transaxle. At the bottom end of the scale, I would use a salvage yard Eaton M90. In a perfect world, money no object a Sprintex S335 or a TVS 1650. For crazy power, like over 500hp, I would go with bigger versions of either.

On the subject of headgaskets, I have never had a single one blow. That said, I always followed the Jim K. guidelines which say to re-torque multiple times until the nuts no longer turn farther at a give torque setting. In my experience I have had to re-torque twice (for a total of 3x).

The difference in discharge temps between a Sprintex, TVS, Rotrex are minor. After the intercooler removes 80%-90% of the heat, I think the difference is insignificant.

Compression: The new Fiat 500 Abarth runs 18 pounds of boost with 9.8:1 compression, and that's pretty normal these days. Of course it has really good engine management and combustion chambers shaped for the job.

10:1 or 10.5:1 shouldn't be a problem at 5psi. My old L-Jet GTV6 ran stock cast 9:1 pistons and NO intercooler with 10psi from an Eaton/Magnuson MP62. It has water injection, but still, it had a now obsolete supercharger and 10psi.

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Re: Supercharging a GTA 3.2 24v motor into 116 GTV -ideas ?

Post by 75evo »

Greg,

Will big cams help to mitigate the high static compression? Do you still have pullies or brackets after the inventory reduction sale you had?

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Re: Supercharging a GTA 3.2 24v motor into 116 GTV -ideas ?

Post by Joemart »

Hi ... I can get my hands on an Eaton, with casing stamped "206122".... From what I can see it is an MP45 or equivalent - is that correct?? - I guess that would mean that it is too small??? - I think it is off a Merc - probably 230
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Re: Supercharging a GTA 3.2 24v motor into 116 GTV -ideas ?

Post by Duk »

Joemart wrote:Hi ... I can get my hands on an Eaton, with casing stamped "206122".... From what I can see it is an MP45 or equivalent - is that correct?? - I guess that would mean that it is too small??? - I think it is off a Merc - probably 230
Use 2 of them, Aston Martin style. 8)
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Re: Supercharging a GTA 3.2 24v motor into 116 GTV -ideas ?

Post by Greg Gordon »

Zamani,

I don't have a good answer for you about the cams' effect on effective compression. I understand the theory that says hot cams will in effect lower the effective compression ratio, however in practical terms, I am not so sure.

I don't know all of Eaton's casting numbers, but a 45ci in too small, except for a very mild 2.0 Nord. The 62 is great for a 2.5, and OK for a 3.0. A 3.2 24V certainly needs 90ci.

Twin blowers are essentially double trouble. Twice the fabrication expense and a belt drive that's going to be 3 times as complex. There are however two reasons to use dual superchargers. One, sometimes that's the only way you can fit everything. It's possible that Aston didn't have room for an M90, but twin 45s fit. Second, if, and only if you set it up with a big supercharger turning slow blowing into a small supercharger spinning fast (i.e. an M112 blowing into an M62) you can get away with some crazy boost and power. That's what Alfa Romeo did on the 159 Grand Prix car. Over 30 pounds of boost on a 1.5 liter 8cyl making well over 400hp.

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Re: Supercharging a GTA 3.2 24v motor into 116 GTV -ideas ?

Post by Duk »

Greg Gordon wrote: Twin blowers are essentially double trouble. Twice the fabrication expense and a belt drive that's going to be 3 times as complex. There are however two reasons to use dual superchargers. One, sometimes that's the only way you can fit everything. It's possible that Aston didn't have room for an M90, but twin 45s fit. Second, if, and only if you set it up with a big supercharger turning slow blowing into a small supercharger spinning fast (i.e. an M112 blowing into an M62) you can get away with some crazy boost and power. That's what Alfa Romeo did on the 159 Grand Prix car. Over 30 pounds of boost on a 1.5 liter 8cyl making well over 400hp.

Greg
At 5.3 litres and 4 valves per cylinder, I'd guess that both of those Aston Martin superchargers were M62.
I think Aston Martin did it like that just because they could. Who had churned out a twin supercharged engine before they did? And besides, it looks awesome. Hate to have to work on it though, start at the top and work your way down :( .
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