New Turbo S questions

[Genifer Teal]

New Turbo S questions.

My background is that I know basics of how cars run. I have tuned a supercharged engine so I am familiar with boost. However, I am brand new to Beetles and especially turbos. I get the concepts, I just have no experience with them - YET.

My car came with some chip tuning. Lets start there. It was a level one ecu reprogramming by (dare I say) EIP. I'd like to learn more about this mod but since they are gone (no need to explain) where can I get info on what they may have done?

My car has a greddy (I think) blow off valve - or is that called a bypass valve? Anyway I hear the boost release when I let off the gas. I don't think stock cars do that - or is it just less noticeable? What I am also noticing and is my main question is that when I give part throttle - enough to create boost - I feel the boost initially but then it goes away while my foot remains at the same part throttle position.

A possible reason for this is that as the car accelerates (moderately) the load gradually lessens on the motor. Less load = more vacuum which eventually signals the valve to vent (recirculate I hope) the boost even though I have not lifted my foot from the part throttle position. I hope you are still with me. This makes sense (to me) so far. IMHO, the boost seems to disappear too quickly. I am not familiar with how quick is quick for the boost to "run out". Can anyone try to explain?

Keep in mind I am talking about part throttle. Under full hard acceleration the boost remains for a much longer time. It just seems like as I shift I'm constantly in and out of boost and it is really noticeable. Is this normal (considering the mods)? What should I expect?

Thanks for your thoughts on this.

Gen

[99Turbo]

Hello and welcome.

If I understand the system correctly the Beetle Turbo system is designed to send any extra pressure back around through the system, not blow it off.

Search the threads for "blow off valve" & "diverter valve"; you should find some knowledgable info on this. From what I have read the BOV will cost you performance not help it.

What I have installed on my car is a 710n diverter valve. The "n" is an improvement over stock with a stronger spring.

As far as performance my '99 responds this way to boost, when I am boosting if I keep the accelerator in the same position the car's speed just keeps increasing (rapidly) and will do so to whatever the max is at that position.

Beetles are known for pulling strong from fairly low rpm's to near the limit.

What you are experiencing does not sound correct and may be due to the BOV. Some people install them because they would rather have the noise than the performance.

[kaiser]

eip's chip tuning ability was marginal at best.
i have no clue as to what thier 1.8t chip is capable of.

quite a few people have had part throttle issues with a varitety of chips.

i would get rid of the bov and go back to a diverter valve that recirculates the excess boost. bov's only work well on cars that run off a map sensor, your car runs off a maf and a map.

start there and see how it drives.

[99Turbo]

I knew someone here would be able to explain the technical why of Diverter valves instead of BOV's.

Oh and as to why your Turbo S has a BOV installed. I give you this from another site:

"Jetta.Curtski
New User | Posts: 5 | Joined: 10/08 Posted: 11/01/08
02:44 PM
Does the DV serve the same purpose (or make the same sound?) I just love the sound of a BOV excites me well beyond any woman could."

Bet you wipe the whole interior down with Alcohol after that

[Genifer Teal]

Thanks for the replies.

I'll except the sound only if it gives me dramatic improvement in performance, otherwise it reminds me of the very old trick of flipping over the lid to the air filter so you could hear the rush of air enter the carburetor. Sounded impressive but did very little for performance. Seems like no point to mod something just to make more noise.

I'll check into the archive for more info on the matter.

Gen

[mat3833]

BOVs can provide a performance increase.... but not in our case. on a high HP car a bov can let the boost out more quickly which keeps the turbo spinning freely. i personaly am getting an HKS SSQV BOV because it is adjustable and i like the sound. no real performance gain until im pushing 30psi of boost but still.

Matt