boost question

[torresmd]

Hey guys just a couple of questions regarding boost. I have had my 930T for a couple of months now and still loving it. I have noticed that boost starts to come on at about 3500 rpm and then takes a long time to get to 1 bar. To me it feels like a lifetime. Is this normal, and is there something that I should check out?

In the very near future I will be upgrading to new headers and exhaust to hopefully help with this delay. Is there anything else that I can do?

Current set up is a garrett turbo not sure which one, cannot find anything on the turbo to help me ID it. Also sc cams.

I have been watching youtube vids of other 930 turbos and they seem to build boost much faster and seem much more responsive. Probably should let another 930 owner drive my car. I have not ever been in another 930T so it is hard to compare.

Thanks,
Steve

[JMA-RUF]

Check that you don't have any vacuum leaks etc. That'd be the first place I'd check.

[Helmsy]

What headers/exhaust do you have on there now? Sounds like it has had a little bit of work done to it so maybe just a leak somewhere or maybe a turbo issue.

It would be handy to know what turbo you have and if there is any smoke/oil issues you have noticed.

And as always photos plz...

[torresmd]

I have stock headers and exhaust right now. However their is no catalytic converter. I do smoke for just a few seconds occasionally at start up. But my 996TT does this as well so I figured it was normal. I also noticed that the O2 sensor is not connected, and I have left it that way. The car seems to run very good, and boosts to 1bar and holds to redline, just kinda slow to get there. Maybe I am just used to the violence of the 996. Also I was watching some vids of 930T on youtube and it just seemed that they built boost much faster. This could be my imagination.

Maybe it is that I am not used to the long gears. When I turn a corner in 2nd and gun it, it seems to take forever build boost. I often hear people give advice to the new owners to make sure you are pointing straight before hammering it. I have yet to feel the danger. I have noticed that if I am cruising at 4K rpm, than yes it comes on fairly quickly but 2.5-3.5K, she takes her sweet time.

I will ID the turbo soon.

[RarlyL8]

2500-3500rpm with slow response is the characteristic of an old 3LDZ or 7006 turbo. Hammer the throttle and count to 5 then hold on! Even my old 7200 11.11 has that charcteristic to 2800rpm.
This is not to say that you may have a leak somewhere or heat soak, etc as well.

[DDDD]

"I have stock headers and exhaust right now."
"Current set up is a garret turbo however I don't know which one."

Steve, I think you explained a lot of it right there. A set of B+B headers will give you 35 horsepower and much better throttle response. Also a member here is working on a set of 993 headers to fit right onto a 930, and that will be dyno tested soon. That is a new hybrid product which could have a lot better quality and price than B+B, although horsepower gains are still to be determined.


Rarlyl8 has several light weight mufflers and straight pipes.

And who knows what size turbine you are pushing, it could be a huge mismatch.

[jwasbury]

Maybe it is that I am not used to the long gears. When I turn a corner in 2nd and gun it, it seems to take forever build boost.

Are you talking about a low speed corner around town? If so, you need to be in 1st to have any fun. 2nd gear is for two lane backroads with posted speed limits of 50-55mph. I'm talking about the one's where the twisty bits have yellow warning signs with suggested speeds of 35mph on the sharper corners(which you end up doubling on the corner exit). When I blast through one of these roads, I'm in 2nd, don't shift at all. On these roads 2nd is perfect, as you can roll into the throttle at the apex and be hitting the meaty part of the torque curve as you exit the corner. I drove my car home on the Blue Ridge Parkway after purchase...2nd gear practically the whole time.

[krasuskyp]

Originally Posted by jwasbury

Are you talking about a low speed corner around town? If so, you need to be in 1st to have any fun. 2nd gear is for two lane backroads with posted speed limits of 50-55mph. I'm talking about the one's where the twisty bits have yellow warning signs with suggested speeds of 35mph on the sharper corners(which you end up doubling on the corner exit). When I blast through one of these roads, I'm in 2nd, don't shift at all. On these roads 2nd is perfect, as you can roll into the throttle at the apex and be hitting the meaty part of the torque curve as you exit the corner. I drove my car home on the Blue Ridge Parkway after purchase...2nd gear practically the whole time.

sounds like a fun ride - I'm picturing it now... sigh.

I was thinking the same thing on being in 1st Jacob. Steve, depends on how slow a 2nd gear corner you're taking. It could be 1st is more friendly in those situations. Prob then is it takes your double clutch deftness to defy 1st gear synchro idiosyncrisity, uh huh.

Before wondering about car issues, I was going to ask 'in what gear do you mean?' Boost onset varies gear to gear and by scenario. So the lag'd onset in 1st - sure - as late as 4000-4200. 2nd-4th, more in the 3500 range but sometimes 3800 if mess up the situation enough.

'Tis def. a whole nuther animal from that of your twin k24'd TT. And that's a good thing 8-).

The point it straight and hold on is there, you'll start finding more of it as your settle your technique in with it as the miles pass. Sure is fun. Forevergears are adddddddictivvvvvvvve (hence my profile 'location')...

Def. give it a twice over tho to ensure nothing awry in thar...

[torresmd]

I took my car for a cool morning drive. I kept it above 4K and the car felt and handled like a race car. If I accidently let the RPM's drop below 3K, back to hurry up and wait for boost. As far as taking a surface street corner in first, well it is impossible for me to shift my car into first unless I am at a complete stop. Not sure if you guys experience this as well. Sometimes I have to come to a complete stop, then shift into 2nd, then first is much easier.

After my header and exhaust installation, I will see how the car feels. I will also dyno and post the results to make sure everything is OK. I truly value the opinions on this forum. The knowledge in incredible.
Thanks!

[DDDD]

Originally Posted by torresmd

I took my car for a cool morning drive. I kept it above 4K and the car felt and handled like a race car. If I accidently let the RPM's drop below 3K, back to hurry up and wait for boost. As far as taking a surface street corner in first, well it is impossible for me to shift my car into first unless I am at a complete stop. Not sure if you guys experience this as well. Sometimes I have to come to a complete stop, then shift into 2nd, then first is much easier.

After my header and exhaust installation, I will see how the car feels. I will also dyno and post the results to make sure everything is OK. I truly value the opinions on this forum. The knowledge in incredible.
Thanks!

Okay the famous not shifting into first could be a number of things but starts with design flaws of the old tranny. You always want to shift sequentially if you can, especially when coming to a stop. 3rd into 2nd into 1st. Not for instance 3rd, clutch in, coasting to stop and then try to put it into first. But 3-2-1.

Here is a list of everything else you need to check anyway when you get a 930:

Clutch adjustment to make sure it goes into every gear correctly.

Are the shifting bushings all in new condition... there is a ball bushing at the bottom of your shifter and two other bushings, all in the shift tunnel.

Finally your engine and tranny mounts must be in acceptable condition. Swapping in wevo semi solids is the way to go, IMO. But that increases noise if you do it to the tranny mounts.


Not saying you need all or any of the above but that covers the bases.

[torresmd]

Ahhh the old 3-2-1 shift. I will try that. I have just recently switched out all the bushing using the directions in 101 projects. Maybe I will work on clutch adjustment next. Not sure if I want to tackle that myself or not. I actually enjoy all of the idiosyncrasies of the car, yes she is old but is also imo the best car ever made. I enjoy taking care of the car and fixing what needs to be fixed.

[jwasbury]

Steve,

I've had my car for over a year now (and about 5,000 miles of smiles). I feel like I am only just getting comfortable with the downshift into 1st. I had the tranny rebuilt, and even with brand new dogs and sliders, the 2nd into 1st downshift is not easy. I have read that a newly rebuilt box needs time to "break in," so it might be that its getting easier as the new parts wear-in. More likely, its that I am getting more comfortable in the car and honing my technique: preferably double clutch and mash the throttle to get the revs up and she slides into 1st while underway without much effort. I took her for a spanking around my neighborhood one day last fall after I finally fixed an annoying acceleration stumble, so I was really pumped. Without thinking, I nailed the 2nd to 1st downshift rounding a 90 degree urban corner and got into the gas (boost came right on) and the ass-end kicked out on me about 12 inches or so...didn't mean to do it, honestly officer

[mark houghton]

Originally Posted by jwasbury

Steve,

I've had my car for over a year now (and about 5,000 miles of smiles). I feel like I am only just getting comfortable with the downshift into 1st. I had the tranny rebuilt, and even with brand new dogs and sliders, the 2nd into 1st downshift is not easy. I have read that a newly rebuilt box needs time to "break in," so it might be that its getting easier as the new parts wear-in. More likely, its that I am getting more comfortable in the car and honing my technique: preferably double clutch and mash the throttle to get the revs up and she slides into 1st while underway without much effort. I took her for a spanking around my neighborhood one day last fall after I finally fixed an annoying acceleration stumble, so I was really pumped. Without thinking, I nailed the 2nd to 1st downshift rounding a 90 degree urban corner and got into the gas (boost came right on) and the ass-end kicked out on me about 12 inches or so...didn't mean to do it, honestly officer

I don't seem to have much trouble getting into 1st from 2nd. Like when tooling through the neighborhood in 2nd gear, heading home to my driveway at a moderate 25 mph, I just let off the gas for some compression slow-down, stuff in the clutch and blip the throttle while at the same time pressing into 1st gear. Usually slides right in at 10mph or so. Be sure to blip the throttle to match the rpm's you'll be at by the time you get into 1st and let the clutch back out.

[krasuskyp]

Originally Posted by krasuskyp

I was thinking the same thing on being in 1st Jacob. Steve, depends on how slow a 2nd gear corner you're taking. It could be 1st is more friendly in those situations. Prob then is it takes your double clutch deftness to defy 1st gear synchro idiosyncrisity, uh huh..

Quoting mesself - there's a new one.

While each gearbox will differ from the next in terms of action / condition / willingness, my above statement is spot on. You need to hone your technique and be on your game. The prob with 'chucking revs' @ a 930 to invoke said downshift is... friggin lack of throttle response. Jacob made good reference to it with "mash the throttle".

But again, depends on the condition of your box and the alignment of the linkages, etc.

Dancing those pedals tho - man - truly what makes these cars so fun.


ps. Jacob, your story had me chuckling - good stuff

[skyturbo]

if you are not toe and heal will be difficult to get 1 in lower reps and in my opinion you can not drive to the full potential without