just another really interesting technical thread.

[Sparkie]

http://www.driftworks.com/forum/technical/50050-dpv.html

[DaveMayGTT]

I wish i understood most of that, anything that reduces lag sounds good to me as a laymen though!

Surprised theres not a few replies on this already seeing as lag seems to be a constant problem with these little engines.

[Markey Mark (BD)]

Thats an interesting read

[Sparkie]

you put a throttle body infront of the turbo inlet and the vacuum the engine produces helps reduce lag.

if you ignore most of the first bit and look at the rest of the thread its explained alot more simply.

[DaveMayGTT]

You gonna try it then Sparkie? Sounds like one of those things you need to try rather than debate for a real answer.

[Sparkie]

the only problem i can see is that you'd have to get a big enough throttle body so that it doesnt restrict the turbo inlet when its fully open.

i think you might have to get rid of any dump valve or run one designed for a car running an airmass meter, that doesnt leak air into the inlet. so that you can get a good vacuum in the inlet tract.

the other thing is, that you wouldnt be able to run the throttle plate fully shut, else how would the carb get any air flow into it? the idle might be abit ropey too.....

[DaveMayGTT]

If you cant run it fully shut wouldnt that defeat the point of it?

[Sparkie]

how did they idle back in the day? - where did the air come from?

[Rob@Backyardracing]

Interesting... so how good does that actualy work? (i havnt read the full thread)... :confused:

[Ben]

how did they idle back in the day? - where did the air come from?
I suppose they were running fuel injection with an idle speed control valve, with the valve plumbed up drawing air from outside the inlet tract or maybe the throttle body has an adjustment screw allowing it to be opened to the required idle point.And another thing is does the throttle body need to open at the same ratio as the carb butterfly?

[Sparkie]

i dont think its a 1:1 ratio with the throttle butterfly.

the idle query, is why i reckoned you would have to open the blockage infront of the turbo slightly on the gtt. or would the air passing through the dump valve work adequately..... ;)

rob.... the theory as far as i can see is that the turbine blades spin quicker in a vacuum. it also directs air into the compressor housing in the direction of the blades....

[Scoff]

in that diagram your right, it isn't 1:1 with the throttle. but on the maxi the dpv was totally mechanical and ran at 1:1 with the throttle.

[Os8472]

in that diagram your right, it isn't 1:1 with the throttle. but on the maxi the dpv was totally mechanical and ran at 1:1 with the throttle.

Go on Scoff, build a prototype

[stuTHC]

A mate of mine with a BBR mazda mx5 is/was very interested in trying this out since i discussed it with him the other week. So he went off and did his own research on the subject. While he was doing it he found this pic-

http://www.rtoc.org/boards/picture.php?albumid=245&pictureid=6075

I just wanted to post it up cos it looks sexy :cool:

It was taken from this thread-

http://www.f1technical.net/forum/viewtopic.php?f=4&t=3012

[Ashy]

you would need all solid boost pipes as the standard ones would just get sucked shut!

[Tiny Tim]

Very nice.

Cable opperated by an ECU in all cases or is there another option?

Could you hook up a counter spindle to opperate against the throttle plate operation?

[Tiny Tim]

Nope, im being a spleen.. they'd work in the same manner wouldnt they.

[boostjunky]

A little off topic, but does anyone know where you can purchase the components to make a turbo damper/support as used on that Gordini engine?

[Saint AAI]

New poster! (less than 10 posts)

This might just be me being stupid, but what would happen if you remove the main throttle body on an EFi car or the throttle butterfly thingie from the carb and just run them straight through and use the throttle body before the turbo to control the airflow?? Then have some sort of idle control valve to bleed air in when the throttle plate is shut to allow the engine to run. I can't see the need for 2 throttle bodies then messing with getting the timing between them right. Why not just move it rather than adding another?

Quick edit: Been thinking a little more on this, you would have to shut the throttle plate completley, then bleed air into the system close to the inlet manifold. The engine should then still get air whilst maintaining vacuum at the turbo. Valve to bleed air in could be a simple mechanical one that opens with the vacuum and closed by a spring, the more vacuum the more it opens so it self regulates and shuts completley when no vacuum or on boost.

[Woznaldo]

There's no skool like the old skool!:cool:

This is definitely worth looking into?

[rs250nut]

Some of the rally cars I used to paint had jack throttles, wide open all the time with some sort of ignition cut to control the idle:)