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Solid Crimson
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ITB Conversion Alfetta GTV 2.0

Post by Solid Crimson »

Hi guys,

I am busy building a high performance NA Alfetta GTV 2.0. The head has been race prepped and has high compression pistons. I have a Gotech-MFI X and need to know which are the best throttle bodies and injectors to run. Also, is there much engineering needed to fit them? (Take into account they need to fit in place of the current Weber 40s) What kind of a power increase will I be looking at?

I have heard about 4AGE/RSi Toyota and/or Sentra Sti ones will these work? I am looking to keep the costs down...

Thanks a stack.
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Giuliettaevo2
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Re: ITB Conversion Alfetta GTV 2.0

Post by Giuliettaevo2 »

Look at a modern sports motorcycle... :wink:

Suzuki GSXR for example. They have very nice throttlebodies on them that can be used quite easy. :)
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Re: ITB Conversion Alfetta GTV 2.0

Post by JohnGTA »

Hi,
Here in SA, Gotech&Glenwood Motors use a local supplier who makes great ITB's, known as DICE(David Ingles).
I'm using them on my 147GTA3.8L, the same size would work ideally on your set-up, 45mm.
Give Dawie De Villiers a call on +27 82 9001926. With the Rand exchange rate you will find the price to be very favorable.
Ciao,
John
85' 3L GTV6(White) number 197off 212, 3.5L
83' 3L GTV6 (Red) number 46 off 212
03' 156GTA(Red)3.7L Turbo
06' 147GTA(Blue)3.8L+6XITB's
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Re: ITB Conversion Alfetta GTV 2.0

Post by JohnGTA »

Forgot....................power wise expect 20-25bhp & obviously it will make a serious improvement at the top end.
When I first tried them it was on a 3.7L 24V in my GTA, this motor at the time was in stage 3 spec, 288degree cams, 11:1CR,big valve heads & with a single throttle body attached to the factory plenum, a larger than stanxdard unit, 80mm in Diameter the car was making 346bhp@6800rpm & this increased to 374bhp@7450rpm. Gives you some idea? However the ITB's will allow you to use some very wild cam profiles & take advantage of a higher CR as now I run them with 304degree cams & 12:1CR & it makes 440bhp.
Ciao,
John
85' 3L GTV6(White) number 197off 212, 3.5L
83' 3L GTV6 (Red) number 46 off 212
03' 156GTA(Red)3.7L Turbo
06' 147GTA(Blue)3.8L+6XITB's
BradGTV
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Re: ITB Conversion Alfetta GTV 2.0

Post by BradGTV »

or jenvy type, which are bolt on replacments for your webers
79 GTV (sr20) 83 GTV (TS) 85 GTV, 76 GT, 84 GTV6, 91 164, 88 75 TS & 89 75 TS
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Re: ITB Conversion Alfetta GTV 2.0

Post by JohnGTA »

BradGTV wrote:or jenvy type, which are bolt on replacments for your webers


Brad,
These SA "DICE" ITB's are identical to the Jenvey's, basically reverse engineered. Locally a set of ITB's for the V6 would hit you at around e2750.00 with duties etc, the DICE inits are about 50% of that.
Results are the same though & I'm sure that there are many ITB manufacturer's that can offer 45mm ITB's.
I can aske Dawie about trunpet length as he has tried many & he has a great data base regarding power,torque, drivability & so on with various CR's & cam profiles.
Ciao
85' 3L GTV6(White) number 197off 212, 3.5L
83' 3L GTV6 (Red) number 46 off 212
03' 156GTA(Red)3.7L Turbo
06' 147GTA(Blue)3.8L+6XITB's
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Solid Crimson
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Re: ITB Conversion Alfetta GTV 2.0

Post by Solid Crimson »

Hi guys,

Thanks for the amazing response. The GSXR ITBs sound... interesting, will check into this! Do they come out as standard on the bike?

@ JohnGTA, the car is a 4 cylinder, not a V6, would the power output still be the same?
Can anyone else confirm the 20-25bhp increase on the 4c variant?

Is it possible to use the Toyota ITBs on the Alfa? Would there be any engineering needed? I am trying to keep the costs down sine they are running away with me at this point in time... both Jenvy and DICE are a little pricey.

Thanks chaps, appreciate all the help and insight!
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Re: ITB Conversion Alfetta GTV 2.0

Post by TS_turbo »

all modern bikes are ITB`s ... but use gsxr 750 ones ..tehy are cheap and most important its posible to separate to 4 single bodies with proper spacers to fit alfa bore to bore centers .... but my advise is use carb bodies :!: just make tapered inserts lets say 45-48 mm to 40 and fabricate TPS mount on throttle shaft :wink: 40mm throttles are enought up to 200 hp ...there is no way to gain 25 hp ONLY from itb conversion on stock nord :!:
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Re: ITB Conversion Alfetta GTV 2.0

Post by JohnGTA »

Solid Crimson wrote:Hi guys,

Thanks for the amazing response. The GSXR ITBs sound... interesting, will check into this! Do they come out as standard on the bike?

@ JohnGTA, the car is a 4 cylinder, not a V6, would the power output still be the same?
Can anyone else confirm the 20-25bhp increase on the 4c variant?

Is it possible to use the Toyota ITBs on the Alfa? Would there be any engineering needed? I am trying to keep the costs down sine they are running away with me at this point in time... both Jenvy and DICE are a little pricey.

Thanks chaps, appreciate all the help and insight!
I was referring to the 2L, 20-25bhp depending on cams,CR etc.
If you are running say a high CR set-up with 300degree cams, then you could expect to see a 20-25bhp gain over say using 45 or 48 side draughts.
ITB's remove the restriction from the venturi's, ie.no choke tubes.
Ciao,
John
85' 3L GTV6(White) number 197off 212, 3.5L
83' 3L GTV6 (Red) number 46 off 212
03' 156GTA(Red)3.7L Turbo
06' 147GTA(Blue)3.8L+6XITB's
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Re: ITB Conversion Alfetta GTV 2.0

Post by la_strega_nera »

Given that guys are topping out at 200-210hp on 48s on the 2ls and TS motors, you're not suddenly going to see 230hp converting to ITBs... just ain't going to happen, and funnily enough, doesnt happen.
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MD
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Re: ITB Conversion Alfetta GTV 2.0

Post by MD »

I seconds that.

It was hard enough to squeeze 200 out of the Brick donk with ITB's.

Mind you, if I had the chance to work on that friggin engine again I think we could squeeze 220 out of it but I would need a house mortgage to fund it. :D
Last edited by MD on Sun Apr 03, 2011 1:49 pm, edited 1 time in total.
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Giuliettaevo2
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Re: ITB Conversion Alfetta GTV 2.0

Post by Giuliettaevo2 »

Solid Crimson wrote:
Is it possible to use the Toyota ITBs on the Alfa? Would there be any engineering needed? I am trying to keep the costs down sine they are running away with me at this point in time...
everythig is possible.. If you can make up a new inlet manifold you can use those Toyota items. :wink: If you have a original carb engine you can have an adapter made that fits between inlet and ITB's. The spacing of the ports needs to match quite good for that however.. :?
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Re: ITB Conversion Alfetta GTV 2.0

Post by JohnGTA »

la_strega_nera wrote:Given that guys are topping out at 200-210hp on 48s on the 2ls and TS motors, you're not suddenly going to see 230hp converting to ITBs... just ain't going to happen, and funnily enough, doesnt happen.

Your statement is logical, however there could be an improvement in power at the lower RPM's but the main advantage with the ITB's would be consistency as you tune them once via the mngmt system & that is that.
My GTV6 3L on the 6xDellorto's is so temperamental, one day as strong as an ox the next day , dead....................I like the set-up, it looks the beans & sounds great but it'sa pain in the ar5e to keep in tune.
It would be nice to see the results of an ITB 2L running exactly the same groceries as a carb fed 45's or 48's.
Ciao
85' 3L GTV6(White) number 197off 212, 3.5L
83' 3L GTV6 (Red) number 46 off 212
03' 156GTA(Red)3.7L Turbo
06' 147GTA(Blue)3.8L+6XITB's
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