What Engine for 500BHP

[turbonutter]

stevieturbo said:

With no signal going to the gate, you would be relying on EGBP to push against the poppet valve and w/g spring.

This will take a lot more EGBP to open this than the base spring pressure suggests.

Normal basic w/g operation is with boost applied to open the gate against the spring pressure, so usually 4psi boost would start to open against your 4psi spring and so on.
Obviously the reality is it is 4psi boost + force of EGBP trying to open the gate, but then once the gate/poppet valve opens the force from EGBP would lessen slightly because the valve is now open and pressure isnt acting against it the same way

Your current setup has boost always applied to lower port blowing it open, and in theory at 100% duty should have this same pressure in the top chamber. So effectively it is 100% reliant on mechanical spring pressure only to fight EGBP.

With a small valve it will take a lot more effort from EGBP to open the valve than say a large valve. Force/area and all that crap.

Ahh - I had understood you meant removing only the solenoid signal to the WG, but you meant removing the boost supply from under the diaphragm as well.

I will put this test on my to do list for when I get home again - right after fixing the clutch!

[stevieturbo]

turbonutter said:

Ahh - I had understood you meant removing only the solenoid signal to the WG, but you meant removing the boost supply from under the diaphragm as well.

I will put this test on my to do list for when I get home again - right after fixing the clutch!

Yes, remove the signal line from boost source, whether compressor or a boost pipe. w/g or solenoid receives no signal at all.

It'll do no harm to configure it as I said anyway, ultimately it will give you more range with no real downsides.

[turbonutter]

stevieturbo said:

turbonutter said:

Ahh - I had understood you meant removing only the solenoid signal to the WG, but you meant removing the boost supply from under the diaphragm as well.

I will put this test on my to do list for when I get home again - right after fixing the clutch!

Yes, remove the signal line from boost source, whether compressor or a boost pipe. w/g or solenoid receives no signal at all.

It'll do no harm to configure it as I said anyway, ultimately it will give you more range with no real downsides.

It was late last night when I read the post, I think the red wine & beer might have affected my thinking

[andygtt]

Do you run one or two waste gates?

On my 3.0L V6 I run two largish tial waste gates (one for each bank) & I only control one side of the wastgates and I have very precise boost control with a huge range, running 0.6bar springs I can run to 2 bar if I choose (have on the dyno accidentally).

My turbo is a Borg warner variant of a S300SX... probably similar size to a GT35... its oil cooled and a float bearing. It spools full boost at around 4500rpm on mine and holds to 8000rpm redline without dropping off. I cap the boost to restrict torque in the mid range as it would make way too much at around 5000rpm otherwise... it makes over 700bhp and 600ftlb.

Based on my experience if I wanted to target a 500bhp max and 7000rpm redline I would run a much smaller turbo so the power band moved down in the rev range... some people in the states have run smaller single turbos on my engine and it moved down to 3000rpm full boost with a 7000rpm redline and they were still seeing 600bhp.

You will need to spec the turbo to match your cam to a certain extent so it is possible your cams do not suit a lower rpm spool, but given the info you have provided and limited knowledge I have my view is you can go down on turbo size... or at least try a smaller exhaust housing on the one you have now?

[turbonutter]

andygtt said:

Do you run one or two waste gates?

On my 3.0L V6 I run two largish tial waste gates (one for each bank) & I only control one side of the wastgates and I have very precise boost control with a huge range, running 0.6bar springs I can run to 2 bar if I choose (have on the dyno accidentally).

My turbo is a Borg warner variant of a S300SX... probably similar size to a GT35... its oil cooled and a float bearing. It spools full boost at around 4500rpm on mine and holds to 8000rpm redline without dropping off. I cap the boost to restrict torque in the mid range as it would make way too much at around 5000rpm otherwise... it makes over 700bhp and 600ftlb.

Based on my experience if I wanted to target a 500bhp max and 7000rpm redline I would run a much smaller turbo so the power band moved down in the rev range... some people in the states have run smaller single turbos on my engine and it moved down to 3000rpm full boost with a 7000rpm redline and they were still seeing 600bhp.

You will need to spec the turbo to match your cam to a certain extent so it is possible your cams do not suit a lower rpm spool, but given the info you have provided and limited knowledge I have my view is you can go down on turbo size... or at least try a smaller exhaust housing on the one you have now?

Just the one Wastegate Tial MVR (44mm)



I think its going to be a case of sorting out th eboost control first (once I am back home) then look at either a different turbo, or possibley a rebuild of this one, with a different compressor wheel... If I had a huge budget it would be easy

[andygtt]

is your turbo twin scroll?

[chuntington101]

andygtt said:

is your turbo twin scroll?

No the Tial stainless steel housings aren't Twin Scroll.

[turbonutter]

chuntington101 said:

andygtt said:

is your turbo twin scroll?

No the Tial stainless steel housings aren't Twin Scroll.

Correct - just the one Scroll.. Something like this:-

[andygtt]

Well I don't know anything about the Alfa V6 firing order etc, but I strongly believe not having the twin scroll on my car would loose me response and spool time as well as power.

[stevieturbo]

andygtt said:

Well I don't know anything about the Alfa V6 firing order etc, but I strongly believe not having the twin scroll on my car would loose me response and spool time as well as power.

I would doubt with any mild cammed setup that a twin scroll ( or perhaps even bigger cams ) actually increases top end power at all.
Anything I've ever heard or read, the twin scroll is all about lower rpm improvements.

Another possible...what diameter are the tubes from head to turbo ? These really dont need to be large at all.

[turbonutter]

I dont remember the exact size of the pipes, but they are not huge....

[andygtt]

stevieturbo said:

andygtt said:

Well I don't know anything about the Alfa V6 firing order etc, but I strongly believe not having the twin scroll on my car would loose me response and spool time as well as power.

I would doubt with any mild cammed setup that a twin scroll ( or perhaps even bigger cams ) actually increases top end power at all.
Anything I've ever heard or read, the twin scroll is all about lower rpm improvements.

Another possible...what diameter are the tubes from head to turbo ? These really dont need to be large at all.

Twin scroll would probably help his spool though?

[stevieturbo]

andygtt said:

Twin scroll would probably help his spool though?

I doubt you'd ever be able to configure all the cylinders for full twin scroll benefits as easy as a 4cyl, but if the banks were divided right into the scroll maybe that alone would see some benefits.
And probably keeping pipe sizes down would help too, especially as overall each bank/cylinder isnt huge.

Problem is, there can be too many damn options !

[turbonutter]

turbonutter said:

Well I guess after 6months its about time to update this thread!!

I did map the car without the turbo, and just an elbow installed in its place, that was back in december & it came out with 220BHP, which wasnt too bad considering it was a low compression engine and was sucking through the charge cooler...

A couple of weeks ago it was back on the rollers with the turbo fitted and the NA map hardly had to be touched, a couple of tweaks here and there, but in the main it was correct. The AEM ECU takes care of the extra fuel needed for the boost internally. Most of the session was spent fine tuning the boost control.

One thing that did show up on the logging is that the exhaust back pressure exceeds the boost pressure, once the boost is above 0.9bar, I wasnt looking for big numbers with this session, so we left the boost at 0.9bar, which is plenty for now. 475BHP and 400lbft. I dont have the graph to post, as I only have a paper copy and that is in the car, while i am back at sea...

Of course just before I left the Clutch went, so as usual I will have to fix the car when I get home, before I can drive it.
Not sure what happened with the clutch, as its an engine out job to check & I didnt have time, but an initial look, found that the driven plate closest to the engine isnt connected to the gearbox input shaft anymore. So either the plate or spline has failed.........

OK Back home again & engine is out, so I finally have the cause of the clutch failiure..... It was my fault, I wish I could blame someone else, but there was only me doing the rebuild. I managed to fit the inner plate the worng way round, i.e. with the nose of the hub pointing to wards the engine instead of the gearbox, which meant only about 1mm of spline was egaged and that was the tapered part. Luckily only the clutch plare spline s damaged & not the gearbox input shaft. I have also managed to overheat & warp the cover plate, but like I said nothing serious - I just need to give myself a good slap!!!

The clutch plates are about half worn & i can just see where the hub has been touching the heads of the flywheel bolts. I need about another 0.1mm clearance to avoid contact with a fully worn clutch - any thoughts on machining 0.1mm from
the bolt heads?

[Liquid Knight]

Use thinner washers?

[stevieturbo]

Depends how thick the bolt heads are to start with ?

But certainly that is a very small amount, and I'd soon have the grinder out, or perhaps ARP make something, and the heads on their multipoint bolts are usually quite thin.

[turbonutter]

stevieturbo said:

Depends how thick the bolt heads are to start with ?

But certainly that is a very small amount, and I'd soon have the grinder out, or perhaps ARP make something, and the heads on their multipoint bolts are usually quite thin.

Just been and checked the bolts. the set that are fitted now have 6.2mm thick heads the others I have are 6.6mm.

But looking at the fitted ones, the head is dished with a 0.5mm lip, so I dont see any issues removing some of that. The clutch plate has already made a start

[stevieturbo]

Surely it was only fouling because that disc was in the wrong way round ?

If fitted correctly, it should clear ?

[turbonutter]

stevieturbo said:

Surely it was only fouling because that disc was in the wrong way round ?

If fitted correctly, it should clear ?

Thats what I thought initially, but the plate was marked on the otherside as well, from when it was fitted the right way round. It is all a bit tight clearance wise, the flywheel ws made absolutely as thin as possible for when I had the alfa gearbox, as there was very little space - now with the Toyota box, it could be much thicker, but no point in buying a new flywheel if its not needed.

Contact with plate the wrong way round:


Contact with the plate the Right way round:


This would probably explain why the clutch has been very "grabby" recently!

[Pumaracing]

Without seeing a photo that isn't so close up I can't quite envisage how the parts fit together to cause this problem but I suspect the proper solution is to have the bolt holes recessed slightly so the bolt heads seat lower down.