2008cc 8.75:1 CR 3A G60 build.

mrbeige wrote:A turbochargers boost level is controlled by the wastegate, and thus the boost pressure will remain constant no matter how the head flows, but the actual amount of air consumed would increase, and thus the turbo works harder. With a G supercharger, the boost is determined by charger speed, and thus the crank speed, so if the engine can consume more air then the manifold pressure will be reduced.





.....I think.....

[/EDIT] Beat me to it Chris

ah I see where kevin question came from now.
Hmmm....
Not really thought about it from the point of view of a turbo.So If you increase the cfm of a turbo engine you will get a kind of double hit as the wastegate will still be set to deliver a certain amount of boost maintaining the same boost pressures even at higher engine ingestion levels as it were?!!!

dirtytorque wrote:ah I see where kevin question came from now.
Hmmm....
Not really thought about it from the point of view of a turbo.So If you increase the cfm of a turbo engine you will get a kind of double hit as the wastegate will still be set to deliver a certain amount of boost maintaining the same boost pressures even at higher engine ingestion levels as it were?!!!

Indeed. The wastegate will still open at the same boost level, but the cfm will have increased. Case in point would be a GT35 on a 12v VR @ 7psi will be working a lot less hard than the same turbo on a 24v VR, as the 24v breathes so much betterer

Ahem...Turbo Talk!!

ctwg60 wrote:Ahem...Turbo Talk!!

Rofl! We'll have you one day....

Do you want me to split this lot out into another thread, Chris?

Nah it's OK. lol

ctwg60 wrote:Ahem...Turbo Talk!!

it's all boost baby.

give or take a few psi.

ctwg60 wrote:What do think of the digi-difficulty with reduced boost measured by the map sensor over the same or larger rev range?

In therory a narrower manifold pressure range should provide greater resolution,but only if you can re-scale your map,i.e you manifold pressure axis to take advantage of this.
Do you understand what I mean by this.
Looking at the attached picture should make that clear.
[You must be registered and logged in to see this image.]

I don't know what kind of flexibility chip tuners have when trying to hack digifant.
Probably not much.If they can't rescale then yes you will loose resolution imo.

Yeah you're right guys, I was thinking turbo again and forgot this engine is supercharged! So yeah, if the engine is able to swallow more boost by way of shifting any mechanical restriction, then the supercharger would have to be spun faster to fill in the void

kevhaywire wrote:then the supercharger would have to be spun faster to fill in the void

Hence my next question to Chris, are you going to offset the better flowing head with a smaller pulley? I can't remember if your charger was standard or not either?

Current charger is a stock item with only 12k on it running a 65mm from new. It's not ported and won't be ported for a good while yet, until it needs a rebuild anyway. Currently produces 11 psi down from 14psi with the old engine.

I won't run a smaller pulley but I will take JMC's research on filters and airboxes and run a paper filter and remove the airbox snorkel and other plastic gubbins from around the airbox, in fact I already have, had a little tinker last night just to see if I could feel any difference and see what the noise level is like. It sounds like it's supercharged now much less muted but not annoying, yet. Does feel a tad quicker over 4k but I couldn't be sure.

I picked up the 3.5 bar fuel regulator today so all set to make the swap. Booked in at stealth for 9am on Friday 11th September. I'll have to leave the house at 6am!!

Gonna swap the head the weekend before so that will be the 4th September I'll be starting to strip it down. I'll do the fuel pump this weekend and get that out of the way.

65mm is small enuff me thinks.
Whats left a 62mm?
Beyond a 65mm if it's not enough for you then you have to re-think the whole g60 thing.

I'll be fitting a 65mm this week.

Yep! Body work time after this head!

and more boost will just compound your digipants fueling issue.

dirtytorque wrote:and more boost will just compound your digipants fueling issue.

Oh, I dunno, if that might help, and the boost range will be larger. I suppose it depends on whether it would give a wide level of boost or just boost lots all the time, if you catch my drift...

I'm glad you managed to get booked at Stealth anyway. It'll be good to see it running to it's best potential

Oh, and I'm keen to see the results of fitting that head JNL has done for you

As I see it the issue is duty cycle.
If he runs even more boost he will need even more fuel for WOT.
I.e bigger injectors.
Which he can't really run because digifant doesn't like large injectors on idle.
Anyway it's a mute point.Knowing Chris he aint gonna fit a smaller than 65mm pulley.
It's just not gonna happen.

mrbeige wrote:I'm keen to see the results of fitting that head JNL has done for you

You're keen! I'm bloody desperate to be put out of my misery on the numbers, I think Stealth's rollers will give more fly torque just anyway but the wheel figures should be about right. I'll still have to take it over to Awesome one last time though.

There is another issue with Digd G60 engines and lower manifold pressure which today I realised and may explain while people are always talking about maxing out there redtop injectors (315cc). The FPR is a rising rate FPR and produces 3bar of fuel pressure at atmospheric pressure at idle the vaccum in the engine will drop this down slightly but as the pressure rises in the manifold so does the fuel pressure in the fuel rail but if your producing less boost you also get less fuel pressure so your injectors are going to be running at a high duty cycle to compensate and thus people are thinking they need bigger injectors when in fact a high rated 3.5 bar FPR may help in compensating for the lower manifold pressure by starting at .5 bar higher to start with!

I worked that out all on my own! Haven't been able to verify it though. I remember testing by fuel pressure live whilst driving to make sure my fuel pump was ok about 2-3 years ago. Pressure from memory was something like 4 or 4.5 bar. The fuel pump I have is rated at 4 bar 100l/h, is that it's maximum flow and pressure or like the FPR is that it's starting point?

ctwg60 wrote:There is another issue with Digd G60 engines and lower manifold pressure which today I realised and may explain while people are always talking about maxing out there redtop injectors (315cc). The FPR is a rising rate FPR and produces 3bar of fuel pressure at atmospheric pressure at idle the vaccum in the engine will drop this down slightly but as the pressure rises in the manifold so does the fuel pressure in the fuel rail but if your producing less boost you also get less fuel pressure so your injectors are going to be running at a high duty cycle to compensate and thus people are thinking they need bigger injectors when in fact a high rated 3.5 bar FPR may help in compensating for the lower manifold pressure by starting at .5 bar higher to start with!

Hmmm, how interesting. That does make good sense, and it would explain why in the quest for better flowing engines some of us are maxing out their injectors. Good point

What manifold pressures are you seeing JMC?

ctwg60 wrote:What manifold pressures are you seeing JMC?

Will check later mate. I have a big valve head and a Schrick cam though, so for example my manifold pressure at idle is quite high.

jmc wrote:

ctwg60 wrote:What manifold pressures are you seeing JMC?

Will check later mate. I have a big valve head and a Schrick cam though, so for example my manifold pressure at idle is quite high.

I'd be more interested in the maximum boost pressure.

Ah ok, I top out at around 12psi at the moment as I have the ISV rerouted into the inlet manifold. Before I did that it was about 10-11psi (slight boost leak which wouldn't go away even after adjusting the ISV). I have a stage 4 charger serviced about 10k miles ago, and running a 65mm pulley on a normal ribbed belt through a Golf G60 intercooler, if that helps. Boost measurements are taken from the small hose just behind the clocks, however that shouldn't affect the reading (apart from perhaps making it slower to respond).

Well I've tested my current fuel rail pressure and it would appear I have less fuel pressure due to less MAP. I'm making 60psi which is a little over 4 bar I'm sure when I tested last time on the green injectors and 65mm pulley I was making 4.5 bar. Hmmm.

So by fitting a 4 bar VR pump and a 3.5 bar reg assuming MAP will reduce again with the new head I should hopefully make 4.5 bar (65psi) rail pressure again. Once it's all done I may test again and see where it's at.

Ordered a fuel pump from TPS £109. Not bad it'll be here tomorrow. The bosch 4 bar one I have will work with the later VR sender. It would just need the current adapter loom removing.

It will be very interesting to see how the eeprom map changes with all of this!

Last night I broke my bloody ring finger on my right hand. Now i have to wear a fringing finger splint. I got stuff to do the next couple of weeks. ****! I think I'll be ok once the swelling subsides.

stop making excuses and get on with it.