ITB's on B series engine

[Stakis]

I would like to ask you to share some experience and power gains with ITB's fitted. What kind of CR ratio you would recommend? when it is worth fitting when not? What diameter ITB's you used? How much gain you got and what specs the car had?

I have information that with ITB's fitted they lost bhp and gained nm. So the conclusion was that it as better with edelbrock manifold. If I remember right the b16 forged engine made 208bhp with edelbrock and with Jenvey ITB's it made 200 bhp only (I believe these were 45mm ones). The CR was like 12:1.

Thank you in advance.

 

[Kozy]

As far as I know, the ITBs don't 'need' compression directly, however you do need to use cams that will make the most of increased port velocity, and it is the cams that may require extra compression.

Only as I understand it, I could be wrong.

 

[Stakis]

But there is no plenum chamber for them, so I believe the loss comes from air flow which flows too easy/unrestricted (compared to normal style manifold)? So can you explain how the gain comes when using ITB's? What makes them work better than single throttle body? I believe bigger overall plot of air suction won't give more power?

 

[turn it up]

But there is no plenum chamber for them, so I believe the loss comes from air flow which flows too easy/unrestricted (compared to normal style manifold)? So can you explain how the gain comes when using ITB's? What makes them work better than single throttle body? I believe bigger overall plot of air suction won't give more power?

I don;t no loads about itbs but from regular reading and talking
itbs seem to be more for mid range power. and gains are got from all the runners being excatly the same lenght and same air flow entry. intake manifold slightly different runners and diffferent air entry into the runners

 

[Kozy]

But there is no plenum chamber for them, so I believe the loss comes from air flow which flows too easy/unrestricted (compared to normal style manifold)? So can you explain how the gain comes when using ITB's? What makes them work better than single throttle body? I believe bigger overall plot of air suction won't give more power?

Less throttled volume - Better throttle response as there is less mass of air to move.
Less inlet restriction - Better volumetric effeciency from a higher 'manifold' pressure.
Faster port velocity - Better volumetric effeciency from higher effective flow rate and ram charging.
Tuneable power band - Change the trumpet lengths for variable pulse tuning ranges.
Less weight - Obvious
Looks - Awesome
Sound - Sexual

As for them being for midrange power, it totally depends on how they are set up. Long narrow runners are going to be good for midrange, but wide short ones are going to be better for high RPM.

The fact is, Honda did a very good job with the stock intake system, so like most things, ITBs won't yield much on their own, as the demand is not there.

 

[clockwoRk]

The only one I really know of atm has this set up. Using an Emerald K6 ECU I believe.

B16A Block
B16A Balanced Crank
Carrilo Pro A-Beam Rods
CP X-Style 9cc Pistons
P72 Head
Brian Crower Springs & Retainers
Brian Crower Stage 2 Cams
Jenvey SF ITB's
AAS 2.25" Custom Exhaust System.

Couldn't tell you what that is with regards to CR etc, it's all just jibberish to me lol

 

[rs250nut]

I'm trying to work out how you would lose hp and gain torque, if torque remains at a constant or flat if you like if you add more speed (revs) you will gain power, not trying to be an ass.

 

[Tony topperformance]

Last year I built a b18 for my old dc2, basic spec was eagle rods, je high comp pistons, skunk valves & springs, Brian crower stage 2 cams, and jenvey itb's, management was mbe 9a4 and pico high flow injectors.

Result ? Lots of power but no torque! It was an absolute screamer, the mapping sessions were interesting, in the end we limited it to 9600rpm, I wants to go higher though, I even tried some stage 3 cams as well but that just moved the power up the rev range.

We are putting it in a race car now & will dyno run just to see how powerfull it is

I will post results when we have them.

Tony

 

[Stakis]

what comp are the pistons? what diameter ITB's? It would be nice to see numbers. But we will not have nothing to compare them. I am looking for as much info as possible for comparisson. Let's say you used skunk2 mani with 70mm thorttle and just fitted ITB's and what this change made in dyno plot.

I want to gather this information as I have TWM 52mm ITB's and I am wondering if it's worth to fit them on my motor.

My engine is:
b20z1 + b16 head (stock CR, so about 10:1)
skunk2 pro2 cams with s2 springs and retainers
hytech try y header
skunk2 inlet mani + 70mm thorttle body

My setup makes 242bhp and 200nm atm.

I plan to fit RS Machine cast pistons to rise a CR alittle bit (the CR will be about 11,4:1 if I am right??), so I am in doubt to fit itb's with this piston change or not.

I also have skunk2 pro1 cams, so I am also thinking that they will work better in my setup as I am revving the engine only to 8600rpm. What do you guys think?

Thanks for all the input.