quad TB's AND turbo

gse_turbo · Post by **gse_turbo** » Tue Oct 23, 2007 11:46 pm

i've been helping some guys on suzuki-forums.com with their plans to run a dual TB in a Reno. after some research i got to thinking about taking a factory manifold, cutting the runners off the collector and welding on a webber quad TB flange.

so now i'm thinking, what would the benefit of doing this and making a collector of sorts before the webber setup to work with a turbo setup.

if anyone fallows what i'm saying let me know what you think.

in the meantime i'll work up an illustration.

garrett

jidasas · Post by **jidasas** » Wed Oct 24, 2007 12:36 am

seems to me the main benefit would be the ability to more easily control how much air goes into each cylinder and more easily avoid one cylinder running richer or leaner than the others.?
I know some engines have a real problem on boost with one cylinder that will run lean while the others are fine.

Jimmy

mezomaster · Post by **mezomaster** » Wed Oct 24, 2007 1:10 am

+1

plus i guess the webber setup would be much more useful and improves alot more the performance in a very high compression ratio engine cuz these engines which runs on high comp. needs much more air and needs the air to go through very easier than a stock manifold, specially cuz the pistons should take the effort of sucking the air...of course it would help also in a turbo setup and also would be noticable improvement for sure but not as much as it would be noticed in a non turbo high compression engine, cuz turbo is already forcing the air to the pistons....

anyways, thatis only an openion

but if i could, i would get that wepper flange even if i have a turbo engine, it still improving performance

Audacity Racing · Post by **Audacity Racing** » Wed Oct 24, 2007 3:08 am

A cheaper and probably easier solution would be to just run a properly tuned manifold with an appropriately sized and shaped plenum. Individual throttles on a turbo application would be a waste unless you could control each butterfly independently to provide the correct flow into each cylinder... meaning you'd also need 4 flow sensors of some description and potentially an O2 sensor for each exhaust primary.

Post by **Efratech** » Wed Oct 24, 2007 1:45 pm

why??? even on a single throttle body is enough.

if its NA, then its different

Post by **PrecisionBoost** » Wed Oct 24, 2007 2:14 pm

Audacity Racing wrote:A cheaper and probably easier solution would be to just run a properly tuned manifold with an appropriately sized and shaped plenum. Individual throttles on a turbo application would be a waste unless you could control each butterfly independently to provide the correct flow into each cylinder... meaning you'd also need 4 flow sensors of some description and potentially an O2 sensor for each exhaust primary.

The extra sensors would not be neccissary if you simply had the intake tuned on a flow bench prior to installation.

Realisticly if your tuning your manifold you need a flow bench anyways.

A Quad throttle body with trumpets will allways be one of the most efficenct intakes, and it would make the throttle response extreemly quick.

About the only thing that beats a quad throttle body setup is a barrell throttle..... but that's just crazy.... and probably not that practical for a road car.

One thing to keep in mind is first gear..... GsiTurbo allready has a hell of a time in 1st because the throttle response is so good on his 2.0L turbo.

Basicly he almost stalls it or it instantly jumps to 3000 RPM.... it takes very little movement of the pedal to go between these two points at idle.

Tom is standing here and read what I said.... he said that the difference between idle an 3K is just 7% throttle opening according to the EO-1.

gse_turbo · Post by **gse_turbo** » Wed Oct 24, 2007 4:18 pm

thanks for the input guys, i'm glad that my rambling was understood. i guess the next step (outside of more debate) would be to take some measurements and work out the logistics.

one more question, i've only worked with a webber carb setup so i know little about there FI systems. so the question is, is the idle air controlled mechanically by how much the butterfly is opened or is there a separate passage and IAC sensor?

garrett

mezomaster · Post by **mezomaster** » Wed Oct 24, 2007 4:23 pm

in both cases cars (turbo and non turbo cars) u would feel a difference and a very large improvement in performance with webber quad throttle flange.

but on the NA car, the improvement would be really large and noticable and the throttle would be so much responsive way more than stock manifold, as u removed a large effort from the pistons sucking the air and just gave them the air really easier than before...

but on the turbo car, u still would feel the improvement and u still would be satisfied of the gain in power u will get, but its just not as much as the NA car with webber, because the turbo is already forcing the air through the manifold into the pistons, so the pistons already takes thiere enough amount of air without any effort to suck it from the stock manifold...

gse_turbo · Post by **gse_turbo** » Wed Oct 24, 2007 4:39 pm

gse_turbo wrote:
one more question, i've only worked with a webber carb setup so i know little about there FI systems. so the question is, is the idle air controlled mechanically by how much the butterfly is opened or is there a separate passage and IAC sensor?

another question, with the stock manifold you get a TON of reserve air because of the distence from the TB to the head, like a giant TB spacer. so if i were to build one of these then the TB's would be about 6" from the head, so what's the down side?

garrett

mezomaster · Post by **mezomaster** » Wed Oct 24, 2007 6:07 pm

some of the idling systems can work on the butterfly or the quad butterflies here by adjusting them to keep the engine idle...otherwise u will need a single passage for the IAC which is installed parallel to the butterflies, which means the IAC is another passage for the air to go throught it to behind the butterflies so it can keep supplying the engine with air when the butterflies are closed...

by the way what u mean with: "whats is the down side?? "

Audacity Racing · Post by **Audacity Racing** » Wed Oct 24, 2007 6:13 pm

I guess that's my point in a nutshell... why do individual throttles if it kills your plenum volume? You'd be far better off with properly tuned runners with bellmouths inside the plenum. The throttle response argument is easily over-turned by the shift-point power argument. Having no plenum volume means when the BOV opens there is no reserve air except what is in the small amount between the throttle and the valve... meaning you'd get insane bursts of power when the air comes flooding back by... in all honesty, not driveable for the first few gears (plus who knows what you'd break in the process)

Something like a Magnus Motorsports style manifold with a large bore throttle (90mm from a Q45?) would deliver better power delivery... at least a more controllable power delivery. This is why you see such massive plenums on high performance turbo cars (i.e. Audi R8-R10 LeMans cars or the Bentley Speed 8 EXP)

Magnus manifold...

Audi/Bentley engine...

gse_turbo · Post by **gse_turbo** » Wed Oct 24, 2007 7:06 pm

Audacity, i like your thinking however it seems that with the Magnus manifold, to optimize the design you'd have to keep the manifold at max pressure at all times so that each port gets the same amount of air forced in. at idle when the engine is creating vacuum the first cylinder would be getting most of the air and the remaining cylinders would be scavenging progressively less air. in all likelihood i may be wrong, but to me this would appear to give a rough idle and may cause a momentary air/fuel inefficiency at low RPM.

i can't really speak on the Audi system other then to say the pics are NIICCCE! i'd like to see the production pics of those manifolds.

garrett

gse_turbo · Post by **gse_turbo** » Wed Oct 24, 2007 7:10 pm

hopefully i don't come off being stubborn, i like what this topic is becoming and everyone is putting out great ideas and theories hopefully it keeps going.

Audacity, i my need your help with a tapered flange if this goes into testing.

garrett

Audacity Racing · Post by **Audacity Racing** » Wed Oct 24, 2007 7:11 pm

Well it's not quite as obvious on the Magnus as it is on the Audis, but both systems have a tapered plenum to keep the proper pressure at each intake runner. It takes a bit of math to get the right taper/volume change... but it's fairly simple when it's all said and done... (the first cylinder needs 4 times the volume as the last cylinder in order to keep the volume of moving air uniform... shape is up to you)

The beauty of the Magnus system is that it's a folded sheet-metal manifold with the trumpets welded into a bottom plate. Very simple design in both practice and fabrication.

Audacity Racing · Post by **Audacity Racing** » Wed Oct 24, 2007 7:16 pm

By the way, if you want to get an idea of how some things work, try this 2d CFD program (web-based). You can quickly figure out how flow will occur in a manifold (click the color option for better visibility)

http://www.bfg.uni-freiburg.de/Projects ... idLB_html/