As above im waiting on a Prv and Gtech1.

My currunt mods i have are
*Hybrid unit(standard casing)
*K+N panel filter
*Dv30
*Boost gauge

Im woundering what sort of boost should i run when i install the Gtech and Prv, and what would be a safish overboost <img src="/forum/images/graemlins/crazy.gif" alt="" />

1.2Bar max if you still have the standard intercooler.

I'm running the same mods with an ss exhaust and i've been told to keep it just under 1.1bar <img src="/forum/images/graemlins/smile.gif" alt="" />

Yep,

runing on standard smic <img src="/forum/images/graemlins/confused.gif" alt="" />

Thats because you race everyone trappy. <img src="/forum/images/graemlins/tongue.gif" alt="" />
I'm sure 'occasional' 1.2Bar is fine to use.

How much boost will it hold to the redline <img src="/forum/images/graemlins/crazy.gif" alt="" />

Mine holds 12-13psi (about 0.8-0.9 bar). Max boost is 15.5psi in first gear and in 4th/5th it reaches 17.5psi.

I'm not too sure on this whole boost limit thing. As i understand it, you take the max boost reached in first gear as your boost right? But it reaches higher amounts in higher gears (i've forgotten why now). Surely it's safer to measure boost in 5th because being 1.1bar in first you are liekly creeping up to 1.25bar in 5th, and obviously for a lot longer.
Is it ok because you are getting more cool air at 100mph, than at 20mph?

Trappy - your max boost should be measured in 4th or 5th - floor the car at 2500 rpm until about 4000 and see what you get. You'll get more boost in higher gears as the engine is under more load. The longer you run high boost for - the higher the charge temps will get as the turbo is working very hard and creating more heat, IMO if you are going for it in 4th or 5th then go for 1.1 bar. if you call it quits after third or there abouts then 1.2 bar is fine.

am i right in under standing from this thread that if you vary your driving from hammering at low speeds and also at high speeds and using a PRV it would be best to set it a 1.0 bar for a safe measure all round???

Geoff - a standard coop will run 1.0 bar with 1.4 bar overboost.

If you want to raise the boost it depends entirely on three things:

1. What turbo you run
2. Your car's fuelling - chip, pump etc.
3. Your car's ability to cool the charge

A GTEC chip will provide fuelling for 1.3 bar if needed - as long as the fuel pump and voltage to it are in good shape.

A standard turbo will not produce more power at 1.3 bar over 1.2 bar - so there's no point in raising the boost more than 1.2 bar. However a GT28RS can be boosted to 1.8 bar assuming your car is set up to take it, and make more power with it.

As a turbo becomes inefficent (as it's pushed beyond it's capabilities) it will generate more heat. If this is not controlled by an Intercooler suitable for the job then you'll get pre-detonation and engine damage. You'll also get detonation from a fuel mixture that is too lean, which is caused by too much air in relation to the car's ability to stick more fuel it....

So in answer to your question - 1.0 bar on a PRV is totally safe on a car in good shape, but you will get the same performance as a standard car - but without the overboost kick the standard boost valve provides.

A GTEC 2 can fuel 1.3 bar ? So I can whack this up from the 1.2 I'm running atm and blame you if it goes pop ? <img src="/forum/images/graemlins/wink.gif" alt="" />

Thanks suba, sorry to go on and also benny i'm not hi-jacking your thread at least not intentionally anyway. I have standard turbo, cooling, have got a GTEC1 and PRV waiting to put in at the moment so gathering info on the most suitable boost level to have for all round driving as i drive to cornwall a few times a year which is just shy of 400 miles and want to be sure what i set it to wont do any damage. So from the above, i can set the PRV to 1.2 and once i uprate the cooling then will have the option to adjust further from there?

that's correct, however with the standard turbo you will not produce any more power at 1.3bar compared to 1.2 bar and in fact you may produce less power. This has been produced time and time again on rolling roads.

Joe

For a car which has only a prv, panel filter and gtech1 then for regular driving with the occasional fast the prv should be set to 1.2 max (holding around 1.0 - 1.1 bar) and for more spirited driving it should be 1.1 max ?

is that a fair assesment ?

I'd say so, yup. <img src="/forum/images/graemlins/smile.gif" alt="" />

Super <img src="/forum/images/graemlins/laugh.gif" alt="" /> <img src="/forum/images/graemlins/laugh.gif" alt="" /> <img src="/forum/images/graemlins/laugh.gif" alt="" /> <img src="/forum/images/graemlins/laugh.gif" alt="" />

yep - set the boost in 4th gear to the max you get as the car comes on boost. <img src="/forum/images/graemlins/smile.gif" alt="" />

Why don't Rolling Roads use the longest gear (5th or 6th) when checking fuelling and boost?

Don't you need to think about the clutch ?
I thought a standard clutch could slip if you run 1.2 bar

i dnt understand all this boost businees coming from an N/A car, what is overboost is this dangerous for the car im baffled i just want my car to work fine, LOL!

cos 4th gear does the job fine I guess. <img src="/forum/images/graemlins/smile.gif" alt="" />

no - 1.2 bar on a standard clutch is fine as long as the clutch is not on the way out anyway. The clutch will be under more strain though.

A brief overboost spike is fine unless it's up to 1.5 bar +.

Fitted my boost gauge this morning and went for a run to see what the car produces before fitting the gtech and prv.

boost reading taken at 4.000rpm in 4th gear was a bit of overboost to 1.2bar then dropped to a steady 1bar all the way to the redline <img src="/forum/images/graemlins/smile.gif" alt="" />

I gather mine did'nt overboost to 1.4 because of the hybrid turbo not having to work to hard i guess,
also i got a liminited boost of 0.9 in 1st and 2nd.

Least it seams resonable as a comparison before installing the Gtech1 <img src="/forum/images/graemlins/smile.gif" alt="" />

Spot-on - sounds like your EBV is working fine <img src="/forum/images/graemlins/laugh.gif" alt="" /> 1.2 overboost and 1.0 constant is exactly how it should be, including limiting boost in 1st and 2nd.

In fact if I was you, I would just fit the chip, and then see if you have any fluctuating boost, or overboost problems. The chip will remove the limiter in 1st and 2nd, you should get a sustained 1.2 bar and possibly 1.4 bar overboost, but I think that the general consensus is that a brief spike before the EBV operates is not a problem.

Without wanting to take anything away from Cosmograph and his excellent products, I found the PRV to give a very on / off delivery - fun for a while but the novelty wore off to be honest.

The EBV would give a smoother delivery, and you would stay on your clutch's Xmas card list <img src="/forum/images/graemlins/wink.gif" alt="" />

dont you find the Blitz does exactly the same?

No, not in the slightest - this may be the bigger turbo softening the power delivery, but even on a normal size turbo, if this was a problem, you'd simply lower the gain on the Blitz so it all calmed down a bit.

Yep, just turn the gain down <img src="/forum/images/graemlins/smile.gif" alt="" />

how long(rpm? secs?), should the 'overboost' last ?