mikjel

Hello.

I am an owner of a stock 88 951S. I want to do some upgrades on my engine. I see that many on this list have good experience with guru-products, so I am thinking of maybe going for a guru map kit. I don't know much about tuning yet, but I'm learning more every day reading here.

One of the things I want to improve on my car is low-rpm-boost. Now I do not get full boost under app. 3000 rpm. I hope a map-kit with reliaboost and shims will improve this. Is this correct???
Not big imrovement maybe??

Is it possible to get full boost and good power in my car from let's say 2000 rpm with the right stuff under my hood? What stuff?

Sorry for my bad english.

Mikjel, Norway.

Luke

if you could spool a turbo with only the small amount of energy we make at 2000rpms it would most likely be poorly sized for the displacement.

if you spend that much time under 3k rpms, you might enjoy an S2 more <img border="0" alt="[icon501]" title="" src="graemlins/icon501.gif" />

Danno

"Now I do not get full boost under app. 3000 rpm. I hope a map-kit with reliaboost and shims will improve this. Is this correct???"

It'll bring this down to around 2800rpm or so. The reduction in intake-restriction doesn't do much to lower boost-threshold because you need more exhaust energy to drive up the turbo. This is simply a matter of the turbine geometry, mass of rotating parts, and available energy from the exhaust.

Olli Snellman

Hejsan Mikjel,

If you want to have full boost around 2000 rpm you need to have much smaller turbo (K24 or similar). With smaller turbo you will loose your top end power.
I suppose it's just impossible to get full boost that low with K26 turbos.
If you want to make it cheap just get GURU chip upgrade kit and you get full boost much faster than with the stock system.
You can make it even better with GURU MAP kit.
PS your english is very good, much better than mine ! Rennlister don't mind if you make mistakes, just think you can write english better than they can write norweigan !

Sami951

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Olli Snellman:
<strong>If you want to make it cheap just get GURU chip upgrade kit and you get full boost much slower than with the stock system.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">I think you meant to say "faster" <img border="0" title="" alt="[Wink]" src="wink.gif" />

<img border="0" alt="[bigbye]" title="" src="graemlins/xyxwave.gif" />

Danno

"Rennlister don't mind if you make mistakes, just think you can write english better than they can write norweigan !"

So... ah Sweanders has been kind enough to post a bunch of Swedish and Swiss club chics. When are we going to see the Finnish and Norwegian chics, eh??? <img border="0" title="" alt="[Wink]" src="wink.gif" /> <img border="0" alt="[bigbye]" title="" src="graemlins/xyxwave.gif" />

Olli Snellman

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">I think you meant to say "faster" </font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">thats excately what i ment

Edited it, so now it's correct

Olli Snellman

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica"> So... ah Sweanders has been kind enough to post a bunch of Swedish and Swiss club chics. When are we going to see the Finnish and Norwegian chics, eh??? </font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">i have one half swiss/finnish chic here at home, won't send her over Ok you have allready Swiss & Swedish covered up. I suppose the delivery address is near Santa Barbara??? do you prefer blond or brunette ? <img border="0" title="" alt="[Wink]" src="wink.gif" />

mikjel

So what happens to low-rpm-boost when you upgrade to a turbo for more max-power (like many of you have)? Do you need even more rpm to get full boost? Depends on what turbo maybe?

PorscheLars

Mikjel
Egil (AZ) drives the same Turbo as I do. I get full boost (15 psi)@2500 with my 3.0. Try to get the data from Egil for comparison.

It is possible to get the turbo spooling up much faster than stock but you have to put the turbo nearer the exhaust ports to take advantage of the pulses.. I have seen it done on a 3.0 16v engine. This need some calculations to do it right.

But it is not possible to get this 100% right because of the limitated space we have.

Danno

"So what happens to low-rpm-boost when you upgrade to a turbo for more max-power (like many of you have)? Do you need even more rpm to get full boost? Depends on what turbo maybe? "

yes, it depends upon the turbo. I have yet to see any upgrade turbo that will deliver more air than stock,and improve turbo-lag. It may have the same lag as stock, or slightly worse depending upon exactly how much bigger the turbo is than stock. One of the factors is the geometry of the turbine to compressor sides. Bigger compressors for higher boost and more flow will spool up slower given the same turbine. And there's still only so much exhaust energy at 2000rpm from a 2.5L engine anyway, that's a hard limit that cannot be changed.

But given that fixed exhaust energy, there's still a lot that can be done to improve the low-end response. Ligher-weight components will help reduce inertia. Things like ceramic-composite compressor wheels, Inconel turbine wheels and hollow beryllium axles with ceramic ball-bearings will vastly improve low-end response. The question comes down to, "How much are you willing to spend, in order to reduce turbo lag and boost threshold by 500rpm?" $4k? $7k?

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Olli Snellman:
<strong> </font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica"> So... ah Sweanders has been kind enough to post a bunch of Swedish and Swiss club chics. When are we going to see the Finnish and Norwegian chics, eh??? </font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">i have one half swiss/finnish chic here at home, won't send her over Ok you have allready Swiss & Swedish covered up. I suppose the delivery address is near Santa Barbara??? do you prefer blond or brunette ? <img border="0" title="" alt="[Wink]" src="wink.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Definitely a blonde, preferrably a genuine real blonde. I just hate it when the carpeting doesn't match the curtains, even though smooth hardwood floors are the trend nowadays...