Supercharging a 350 V8

[chedder]

Anybody had any experience in this?, have purchased a Sprintex S102 that is destined to be fitted to my 350, what I need to know is;
1)Best compression ratio and how it was achieved (pistons, spacer gasket etc
2) What dump valve used to relase over boost
3) Where does the engine breather that normally fits onto the plenum, need to be placed
4) As it is currently fitted with a flapper system, what method is used to upgrade the fueling
5) what cam, heads used?
Probably loads more techi questions, so if you can think of any answers please post!

TIA
Chedder

P.S Tried posting in the Wedge section but did not get the info requested

[350Matt]

When you say 350, I think you mean a 350 wedge? so a Rover V8 not a 350 Chevy?

Anyway most superchargers use a bypass butterfly to control the over-run boost this sits in a bypass pipe in front of the charger and leads to the manifold behind the charger.It is operated by engine vacuum so on the overrun the butterfly opens and the engine draws its overrun air through the bypass pipe.


see http://www.magnusonproducts.com/bypass.htm


This also produces less heat in the charger as the air its moving continues to circulate just round and round the bypass circuit instead of being stalled .

If you're only looking at 5-6psi of boost then the standard piston will be fine, but you will need some method of retarding ignition on boost and getting more fuel in there.

I'd strongly recommend throwing the flapper system in the bin and fitting after-market ECU which can control spark and fuel this on its own makes a reasonable improvement, especially if you fit coils. and only keep the dizzy to drive the oil pump.

Matt

[jellison]

I am not really sure on this whole blowing Rv8's and the imits of the std bottom bend art not going to b improved on. i.e. the rev limit in each gear will be the same. A 4.0 or 4.5 might make sense as they have shorter through cranks but the longer you go i.e. the 500 lumps have very long through cranks which make sthem great fro torque (as std the power is not great, but the torque is really pretty good). A 500 really should not be rev'd past 5800 very often if long life is expected from the lump meaning you are really limited on the bhp / and ft/lbs over a wide range. I'd much rather have a heavily worked 4.0 Rv8 than a longer stroke (but cheaper bigger one). Part of why I want rid of my 500 lump was that I felt it was going to go bang at any minute when reving it hard - used to be scared of the possible expense!

[Speed eight]

If this is about the Rover V8 engine, then.....
to cut to the chase.......find out what you can about a guy called Nick Mann.
He use to run a Morris minor with a blown Rover V8.

What there is to know about this subject he will know.
His car was for a time simply unmatchable!

There was once a book, maybe still is, about it all.
I have raced against him and he was the the best of the best.
If you could even match his results you would be in spectacular company.

Good luck with your project and keep us up to date please.

Regards,
Speedeight.

[GreenV8S]

350Matt said:

It is operated by engine vacuum so on the overrun the butterfly opens and the engine draws its overrun air through the bypass pipe.

It's sometimes called a bypass valve/pipe but actually it's a recirc valve/pipe; the air flows in the reverse diraction (away from the engine). The purpose is simply to take the load off the blower under part load to prevent blower heat build-up and wear.

[chedder]

Thanks Guys, have found some info on Nick Mann and also some on Dennis Priddle who was the guy who put the Sprintex units on Range Rovers and the TVR SX originally,.
From what I can see the installation of the Sprintex Supercharger is fairly straight forward, the only snag at the moment is the extra fueling required, currently running a flapper airflow meter, Lucas 4cu ECU and standard injectors, so will probably upgrade the afm and injectors to Jag units, and contact Mark Adams to see if he can sort the ECU.
Installation will be starting in a few weeks, once the power steering pump location has been altered and the brake upgrades have been completed.

[Jasper Gilder]

I've got an SX. It needs thicker head gaskets otherwise youll get a very high compression ratio, much detonation etc. This was the only engine hardware mod.

[Speed eight]

Hello Tony.
I have some experience with forced induction RV8 motors from back in the early to mid 80's.
I remember having some copper head gaskets made to lower the compression to 8.5:1.
Laser cut, using the standard ones as templates. Very cheap too.

It was all a bit of a "black art" back then and we destroyed all sorts of parts.
But when it did work..wow! What a wild ride.
The standard 3.5 when built carefully can take a whole heap of punishment on the forced induction side.
We used standard parts also, but took great care to stress relieve them and weight match parts etc.
One of the best things which we bought was an MSD "Knock sensor" with this in place and a simple MSD ignition control system we could run the timing on a knife edge and get away with it.
We NEVER made as much power with EFI as we did with carbs and the carbs were real easy to work with.

The biggest hold back was the weight of the valve gear. Of course so much more is available now.
In the end we were running at 6250Rpm without problems. Not with the standard valve gear though.

I still think that Nick is your guy if you could get his ear.
I will look back through my archive to see if I can find anything which might be of interest to you.

Regards,
Speedeight.

[chedder]

Thanks Speedeight, any info would be great, already looked at the compression ratio, currently have 9.75-1 and have been informed by a few engine builders that if I use composite head gaskets it will bring that down to about 9.0-1 and that would be quite a good match for the Sprintex.
Alternatively, a 3.9 Range Rover block already has the low compression ratio required, but for the time being will stick with the 3.5 until something goes bang.
Have been looking at the MSD 6AL ignition unit with a plug-in gizmo for ignition retard, seems fairly inexpensive on Ebay (USA) so will probably go down that route to start with but may consider something along the lines of a Megasquirt unit for the future, as that will control fueling, ignition and the Nitrous all from one little black box!

[scooterscot]

Roger Bywater, Dennis Priddle and I developed the SX for Dave Haughan, Dave lent me the original car. I still have an original ECU for the sprintex conversion. Give me a call at work on 01877 331099. We did not build many as Peter stopped us due to the fact that it was quicker than the SEAC. The same basic conversion with a different inlet/blower mounting was used in our Range Rover conversion of which about 70 were built, I ran my blown Range rover for 230k miles but changed to the Autorotor blower as we developed the conversion.Still have a few bits lying about, how much of the conversiondo you have? The inlet was very complex and expensive to build.The only mod to the engine was thicker head gaskets apart from that the engine was standard. The boost was between 6 and 6.5 psi as ther was no intercooler.