Single throttle versus ITB's on 16V...

[jondee86]

I know that everyone has an opinion on how great ITB's are on a
16V, but what I would like to know is, has anyone ever tested back
to back ??

Open ITB's make a lot of noise and create an impression of
"POWAH", but on the dyno, can they actually show any improvement
over a single throttle setup on the same engine ?? So if anyone has
any evidence one way or the other, please post it up.

Cheers... jondee86

[Dell'Orto]

I doubt unless you have some fairly radical cams they'd be a massive gain over a smallport single throttle body manifold.

[QikStarlie]

as above doubt will gain much if anything over a well built single setup. but with itb's is far easyer to tune you inlet, by swapping out different length trumpets. plus will idle better with big cams on itb's

[jondee86]

@ Qik Starlie
Engine actually runs really well with those cams I got from you. They
measured up at 272in/268ex@ 0.006", and with the other top secret
mods I have done, it has a ton of bottom end But building a decent
airbox is gonna be a major pain, as even with short trumpets I am
way too close to the clutch master and brake booster.

I want to try and get this thing legal so I can go to one of the meets
or track days, and the easiest way to do that will be to chuck the stock
smallport manifold back on. Retune, Apexi intake on and fab a cold
air box... done !! Can always go back to the quads after the car has
been certed.

Cheers... jondee86

[Celica RA45]

curved ram tubes are you freind

[Mr Revhead]

On a stock engine any gains would be pretty small, but you might get something from the more direct inlet tract. Also might improve throttle response. The more mods the more likely a gain as they overcome and bottle necks in the stock system.

[QikStarlie]

@ Qik Starlie
Engine actually runs really well with those cams I got from you. They
measured up at 272in/268ex@ 0.006", and with the other top secret
mods I have done, it has a ton of bottom end But building a decent
airbox is gonna be a major pain, as even with short trumpets I am
way too close to the clutch master and brake booster.

I want to try and get this thing legal so I can go to one of the meets
or track days, and the easiest way to do that will be to chuck the stock
smallport manifold back on. Retune, Apexi intake on and fab a cold
air box... done !! Can always go back to the quads after the car has
been certed.

Cheers... jondee86

sweet. how come you cant cert with the quads? brake and clutch masters are the bland of my life

just remembered i did some testing on quads vs a custom single throttle setup, single throttle inlet was roughly same runner length, large plenum (vs stock one) bellmouths and fully tapered runners from belmouth to port. 60mm throttle. quads were silvertop on custom manifold with some average trumpets
did some data logs. bugger all difference, quads slightly better maybe. even if you just compare the rpm trend, you can see it doesnt really accelerate any different. hp numbers obviously aren't correct.

cant remember if i was running standard cams back then or the ones your using.
quads solid line. dotted single.
http://img.photobucket.com/albums/v178/ ... verlay.jpg

[jondee86]

curved ram tubes are you freind

Got some... but getting an airbox around them is another story !!!



Cheers... jondee86

[jondee86]

@ Qik Starlie
How come you cant cert with the quads?

Not so much the quads, more that I have been given to understand
you need a working airfilter setup, and that excessive intake noise
could be a problem ??

Haven't actually been to have a chat with the cert guy yet, so could
be completely wrong about that. But in any event, I don't want to be
rocking open throttles full time. On a bad day you could be sucking
in a lot of dust, dirt, sand whatever, and the noise is a bit over the
top. Wouldn't be so bad if I actually had 500 hp... then at least I
could live up the noise it makes when overtaking

Cheers... jondee86

[QikStarlie]

mine had open throttles at time of cert. dude didn't seem worried about it. was a few years back tho

found there was more room under booster on my ae. bit of a a pain to rebuild your whole setup tho

[evil_si]

How about individual filter socks over each ram tube

[jondee86]

Work of art that ^^^

The reason I liked the idea of quads, was that you can pretty
much guarantee equal airflow to each cylinder when running open
throttles. As soon as you put them in an airbox you are recreating
the flow problems of a log manifold, unless you can use a very
large airbox.

I could build a new manifold to lift the quads up higher. But it is not
going to perform any better than the one I have now, and there will
still be problems in getting a decent size airbox under the hood.
Looking at your graphs, I wouldn't expect to lose much by going
back to the smallport manifold... not at the kind of power level I'm
working with !!

I'd like this thing out of the shed and on the road by xmas, and
once I have it certed, I can always come back and play with the
quads some more. Driveability is more important to me, than a big
dyno number... that is, until I get some high comp pistons in there
and a bit of head work

Cheers... jondee86

[QikStarlie]

yeh cant see it sapping huge amounts of power. but yeh still a bit of a step backwards from what you have

correct airbox can gain you power with quads. i tried one but didn't see any noticeable gains. was bearable to drive for long distances as it quietened it down alot. but at the same time, car didnt make the right noises when hitting the loud pedal. so went back to the pipercross dome filter. we tested the dome filter on dyno. made same power with it on or off. have seen filter socks sap a decent amount of power, wouldn't consider them an option.

na tuning is choice, but sometimes are better off beating your head against a wall.

[d1 mule]

have seen filter socks sap a decent amount of power

a mates beams 3sge with quads list 15 whp with the uni filter individual socks on, back to back nzefi dyno

[4agtepwr]

My little race car with a silvertop running a blacktop ecu and uni filter socks over the factory trumpets and no form of airbox lost over 30hp with the socks on, when i first got it it seemed incredibly dull and rich, we put it on the dyno and this confirmed it, 85 hp and flat 10.0 air fuel ratios, we removed the filters and straight away 115 and a bit lean but that was a combination of a few things and trying to run a silvertop on a blacktop ecu, we rewired and used the g4 out of the mr2 and 122hp and perfect driveablity.
http://www.youtube.com/user/philip22nz# ... cKyvGyn0R8
heres a short vid of it, not the best example as they didnt have the springs in them but there still rather average imo.

Pretty much any filter straight on the end of a trumpet is going to hurt power, with a well thought out air box and a big enough air filter that does not cause a restriction it will not hurt power, pretty much why when you take the factory air box off a blacktop and run open trumpets they go backwards on the dyno but i guess they do sound cool. Helmholtz is the answer as REDMIST would say the air box/plenum is there to create a pulse wave, not just to dull the sound of your sweet ITBS bro

Same with bolting a set of ITBs on to a factory motor, Believe it or not but company's like Toyota and Honda do spend a lot of money on developing there engines/intake manifolds and what not, and generally engines will not make a gain or may make slightly more peak but kill mid range. With a highly modified/high comp/cams with overlap resembling the arms of a straight jacket, this all changes though.