Blow Thru Turbo GTV

[Storm_X]

300hp is alot more then 200 and less. im thinking 3" dump into 2.5 or 2.5 in 2.25

[Darryl]

Whats up Storm,
You've gone all conservative on power output all of a sudden?

[Storm_X]

i never said that.

i was just saying  3" for a car putting out 300hp is ok but 200is fine for a 2.5".

to get from 200hp to 300 hp takes alot of work

[Mike]

How goes this build?  Lets see some pics :-).

On the subject of exhaust diameter, it's definitly horses for courses.  3inch is a good size for 300horse, I agree, and 3inch is a good size for 200 horse also...BUT...3inch weighs more than a 2inch system and at 200hp, maybe you make 5more hp for going the bigger exhaust....hardly worth thew weight and expense.  Of course, I've never met a man that hasn't modded his car to a certain level and then proceeded to chase more power.  I for one would only want to pay for an exhaust once, so would tend to lean toward 3inch.  Out of interest, where are you routing a 3inch exhaust?  Certainly not up over the axle in an Alfetta gtv thats for sure.  Mines a side pipe, cuts down on weight, and avoids me burning brakes, box oil, lines and rubbers.  Just a thought.

I will have my turbodelta shortly and will take a look see at what has been done to the dizzy if you like.  I have also heard they are locked, which makes sense, don't want advance being wound in when boost comes on!  I recall a rule of thumb being to remove 2degrees for every pound of boost.  Did you ever work out your new comp ratio?  what fuel do you want to be able to run on?  Your turbo appears to be oversized for the kind of boost I imagine you will run (like 10 psi max with those rods?).  Do you know what the curves are for the turbo?  Wheres the surge line?  Gotta be careful with this stuff or you end up with a broken motor real fast.  Hopefully you are all over it.

As for your carbie tune, no way are you going to get them tuned properly for 60bucks.  The car needs to go on a dyno, otherwise how are they going to know what the fuel and ignition are doing through the range?  I've tuned webbers on the dyno before...it's time consuming mucking aruond with emulsion tubes and jetting....how many different jets will you have?  Make sure you have a good assortment so you can mix and match.  Emulsion tubes are expensive now so you probably wont have the luxury of a few of these suckers!

Hopefully I am not coming over too negative, just seen a lot of stuff ups in turbo builds.

Nice louver tool by the way, does a great job. 

[BradGTV]

so...
in the last few weeks have managed to get all steam pipe ready to be welded into a 4 into 1 manifold. cut out the flange so it a bit more atractive, rebuilt the dellortos with turbo kits (exept the spindle seals still need to confirm how there done).

been reading some doggey vw buggy forums and several times a boost retard module has been mentioned, i have also heard of it on the benecia turbo motors. sounds like a good invetion! it been described that when boost come on the dizzy automaticly retards the igntion, and it has a boost line from the manifold. does anyone have experience with this?

thanks brad

 

[Alfalfa]

*drool*

[Storm_X]

been reading some doggey vw buggy forums and several times a boost retard module has been mentioned, i have also heard of it on the benecia turbo motors. sounds like a good invetion! it been described that when boost come on the dizzy automaticly retards the igntion, and it has a boost line from the manifold. does anyone have experience with this?
thanks brad

 

ive got a dizzy witha boost retard.

[Duk]

I will have my turbodelta shortly and will take a look see at what has been done to the dizzy if you like.  I have also heard they are locked, which makes sense, don't want advance being wound in when boost comes on!  I recall a rule of thumb being to remove 2degrees for every pound of boost.  Did you ever work out your new comp ratio?  what fuel do you want to be able to run on?  Your turbo appears to be oversized for the kind of boost I imagine you will run (like 10 psi max with those rods?).  Do you know what the curves are for the turbo?  Wheres the surge line?  Gotta be careful with this stuff or you end up with a broken motor real fast.  Hopefully you are all over it.

The only problem with generic statements like "2 degrees per pound of boost......" is that it doesn't allow you to tune for what your particular engine want. There are examples of a engines tolerating factory type ignition advance angles with a few pounds of boost. If you removed 2 degrees per pound, already you would be at 6 degrees less and have lost a heap of torque.
And as for locked timing distributors......... Well, people worked with what they had back in the day. We have and know much more now, so why would anybody massively compromise their overall results with such a set up.

As I suggested to StormX on Alfa BB, use a programmable form of 3 dimensional ignition timing controller. That will give you the best opportunity to get really good overall results with every opportunity to avoid detonation.
I'd much rather have an over fueled carby turbo engine (because it couldn't achieve correct AFR's in every situation) with proper 3D ignition timing control, than a correctly tuned, fuel injected turbo engine and a locked advanced distributor (or the equivalent tune in the ignition map).

I've tuned webbers on the dyno before...

Mmmmmmmmmmm dyno tuned barbecue's! You can taste the extra performance

Storm, how's the turbine wheel? If it's a good turbo, I think you'll love it's response on the Alfa donk (with good tuning  ).

[Storm_X]

Storm, how's the turbine wheel? If it's a good turbo, I think you'll love it's response on the Alfa donk (with good tuning  ).

What do you mean hows the turbine wheel ? If you mean how much shaft play It is still pretty good no give besides the normal really and i might even get another one that was only just rebuilt. Im only using a rb20 turbo to start off with once its all running good etc im going to upgrade. I know it will have awsome responce but im planing to run 15PSI.

[Duk]

The ceramic turbine wheels can get chipped/damaged pretty easy. They are plenty strong, but don't suffer impact (no turbo will). I wrecked a good turbo like that when I tried to take the turbine housing off.
If it's a good turbo, it should survive 15psi for ages. The old 'Ceramic turbine wheel and 15psi' stigma is more related to turbine speed than anything else. 15psi on an RB20 with it's well flowing 4 valves per cylinder head will require a higher turbine speed than a standard head Alfa engine will at 15psi. Just another mis-interpretation that was sprouted off in magazines, accepted as gospel and perpetuated by word of mouth and forums.