Topic: ITB Wisdom

a friend and I are planning and ITB/velocity stack install on the 1987 Honda Prelude, so I am inquiring if anyone has some wisdom to impart, suggestions, advice, share mistakes made, etc.  (there are no kits, adapters, nothing available to make this easier...)

So far, we have throttle bodies off a Honda motorcycle, 2005 CBR 1000RR, and it has a throttle position sensor on it
We are planning some kind of adapter to attach it to the head

---fuel injector suggestions? it seems to be very difficult to find the flow rates to these. Searching, we think they are around 290 cc/min.  The stock infectors on the Prelude are 235 cc/min.  We are thinking of just trying the high flow injectors, then playing with the fuel pressure.  I purchased an ebay adjustable fuel pressure regulator that can hook up downstream of the fuel rail.  I think there was a Honda CBR 600 motorcycle maybe with smaller flowing infectors that might fit...

--plan is to buy little individual air filters to attach to each throttle body

-- I need to find out if I should use the MAP sensor that came with the throttle bodies or the stock Prelude MAP sensor

---I wonder if I will need to get an new ECU....currently it has the stock "OBD-0"....very old, stock one

---I still need to figure out how to run the throttle cable, maybe once I mount it, I will be able to figure it out.  I read somewhere that it is important to check the throttle cable travel, so that mashing on the gas pedal does not pull on the throttle too much,....might need to install somekind of hokey puck under the gas pedal??

---I am installing and Air/Fuel gauge right now, so maybe that will help

---also, unfortunately, timing can't really be adjusted on this car....there is nothing in the little tranny window to shine a timing light at (maybe it was removed when we had the flywheel machined down to make it lighter?)...I think we are running a bit on the rich side, since spark plugs tend to gunk up a little over time, but like after 5 or 6 races, nothing drastic....and the distributor will not turn any further to make it leaner....it is retarded all the way..?I think...advancing the timing makes the car run richer, correct?

- I am probably not foreseeing some problems that are in store for me....

Thanks!

MarioKart Driving School: 1987 Honda Prelude Si (Opus #28) 
Loudon, NH 2014 - Millville, NJ, Lightening 2019 (RIP)
New and improved: 1987 Honda Prelude Si (Opus #11) Pittsburgh, PA 2021 - ??
and finally won something, Class C Win: Loudon, NH 2022

Re: ITB Wisdom

I would think you would need to go with an aftermarket ECU.  As long as you don't need to control VTEC yo, you can use a simple system.

Microsquirt (MS) with a 8' harness is under $400 + another $70 for the software.  MaxxECU mini is a little more expensive, but a little more polished from what I hear.  There may be a plug and play solution for your car as well.

You could probably have it control your existing timing, or convert to coil on plugs.  The aftermarket ECUs use speed density so you just need simple GM sensors to run.  Intake Air Temp (IAT) sensor, Manifold Air Pressure (MAP), Coolant Temperature (CLT), Throttle Position Sensor (TPS), Air Fuel Sensor (wideband is best) and a timing source VR or Hall are pretty much all you need if I remember correctly. 

High impedance injectors are preferred with the MS.  You could use any appropriate and build a fueling table for them.

The other benefit of an aftermarket ECU is the ability to log data while you race for troubleshooting or tuning enhancements.  I have a raspberry pi connected to my MS that logs everything for review later.

Team whatever_racecar #745 Volvo wagon

3 (edited by DirtyDuc 2022-12-30 12:24 AM)

Re: ITB Wisdom

There's a thing called alpha-n in the megasquirt world, which doesn't need MAP sensor. TPS drives load. ITBs have notorious MAP issues, especially with really short runners. They work better with velocity stacks, which are usually built into the bike airbox. Which is the only really good way to give them filtered air.

If your car has a standard dizzy and coil, you can run fuel only with the rpm signal from the coil.

It's pretty cheap to get your injectors cleaned and flowbenched. I use a guy out of Ohio to do it (mrinjector.us). It's like $16 an injector (maybe more now? I last did it in April 22), Plus flat rate shipping both directions. You even get a little report showing before and after.

That guy

Re: ITB Wisdom

DirtyDuc:

He's in ID now, $20 - $25 per injector now. And, he has interesting video about his process; it looks thorough.

He doesn't do *diesel* injectors.

Re: ITB Wisdom

MZAVARIN wrote:

a friend and I are planning and ITB/velocity stack install on the 1987 Honda Prelude, so I am inquiring if anyone has some wisdom to impart, suggestions, advice, share mistakes made, etc.  (there are no kits, adapters, nothing available to make this easier...)

So far, we have throttle bodies off a Honda motorcycle, 2005 CBR 1000RR, and it has a throttle position sensor on it
We are planning some kind of adapter to attach it to the head


-- I need to find out if I should use the MAP sensor that came with the throttle bodies or the stock Prelude MAP sensor

---I wonder if I will need to get an new ECU....currently it has the stock "OBD-0"....very old, stock one

....and the distributor will not turn any further to make it leaner.....?I think..!

No in person wisdom but do know stuff

1000cc ITBS to me, sound small

MAP, hmmm, vac port on each TB and T all 4 to it?

ECU, non airflow meter type? Possibly, find injectors that roughly flow thw same as stock.

Distributor is all about timing, not mixture.  You may need to re find/mark TDC, can you use the lower timing belt mark?

Good luck!

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Re: ITB Wisdom

Lemon_Newton-Metre wrote:

DirtyDuc:

He's in ID now, $20 - $25 per injector now. And, he has interesting video about his process; it looks thorough.

He doesn't do *diesel* injectors.

To be fair, he's been in Idaho as long as I've known about him, I just confused my Dayton's while traveling cross country.

That guy

Re: ITB Wisdom

DirtyDuc wrote:

[snip] ... I just confused my Dayton's while traveling cross country.

I feel the same way about Houston when I'm in TX rather than NYC

Re: ITB Wisdom

Look up the Product Design guys. They've got an ITB setup on the Saturn Twin Cam engine. From a BS perspective, I honestly haven't ever given a crap to look into what ECU they've been running—it's still a pre-Ecotec GM overhead-cam engine—but it clearly put some pep in its step.

Eric Rood
Everything Bagel, 24 Hours of Lemons
eric@24hoursoflemons.com

Re: ITB Wisdom

MZAVARIN wrote:

---also, unfortunately, timing can't really be adjusted on this car.....and the distributor will not turn any further to make it leaner....it is retarded all the way..?I think...advancing the timing makes the car run richer, correct?

If you have no visible timing mark you can create one without too much trouble.
Step 1: Buy or fabricate a TDC Stop. Once, I made one using a spark plug anti-fouler and a bolt that I rounded the end on.
Step 2: Find TDC by carefully turning the engine over by hand with the TDC Stop installed in the #1 cylinder while it is on the compression stroke. As you turn the crank the piston will contact the TDC Stop. Back out the stop's bolt just a little and turn the crank some more. Repeat until the piston just barely grazes the stop.
Step 3: Pick a spot on the front of your engine that you can use as a reference, or make a pointer for the same purpose, that is next to your crank pulley. Mark it/install pointer so that the crank pulley can be strobed with a timing light, and you can see the reference marker.
Step 4: File a mark into the pulley that aligns with the pointer/reference and paint it white or yellow.
Step 5: Index mark your crank pulley so that you can remove and install it in the same position.
Step 6: Use a adjustable timing light to measure spark timing.

Regarding ignition timing: Your spark timing has nothing to do with your fuel mixture during combustion. It will, however, affect the readings of an O2 sensor. Retarded timing will allow some unburned fuel into the exhaust and read as a rich AFR. Running as much timing advance as you safely can will provide more torque, more horsepower, and better fuel economy.

Team Infinniti wrote:

1000cc ITBS to me, sound small

Remember that the Prelude is likely around 2000 cc displacement with a 6500 rpm limit
and the CBR 1000 cc has a 13000-ish rpm limit. Those ITB's are pretty capable of feeding the Prelude.

Regarding fueling control for this project... Speed/Density is the way to go. It looks at engine RPM and size v. ambient air pressure and temperature to compare to 2D tables in the ECU to control fueling and reach a predetermined AFR that is verified by a wide-band O2S.
It sounds difficult, but it's not too hard to learn. Also, with a decent set of starting maps/tables the Mega Squirts can self-tune. That community probably even has a setup suitable for your build.

Capt. Delinquent Racing
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Re: ITB Wisdom

wow! Thanks to all contributors, so far!
I'll try making the timing mark as you suggested!

we do have a hose that goes to each throttle body and connects them all to the MAP sensor....

and I'll shop around for ECU, and do some research on your suggestions....

and might as well get the injectors cleaned and tested...
this one is near me in Massachusetts, not too expensive $68 for 4

MarioKart Driving School: 1987 Honda Prelude Si (Opus #28) 
Loudon, NH 2014 - Millville, NJ, Lightening 2019 (RIP)
New and improved: 1987 Honda Prelude Si (Opus #11) Pittsburgh, PA 2021 - ??
and finally won something, Class C Win: Loudon, NH 2022

Re: ITB Wisdom

What about the https://rusefi.com/ guy?  He's on here and one of us.

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Re: ITB Wisdom

cheseroo wrote:

What about the https://rusefi.com/ guy?  He's on here and one of us.

I saw Andrey at NJMP this year, I think. He's out East somewhere (New York? New Jersey), that's a great suggestion.

Eric Rood
Everything Bagel, 24 Hours of Lemons
eric@24hoursoflemons.com

Re: ITB Wisdom

therood wrote:
cheseroo wrote:

What about the https://rusefi.com/ guy?  He's on here and one of us.

I saw Andrey at NJMP this year, I think. He's out East somewhere (New York? New Jersey), that's a great suggestion.

Andrey lives in New Jersey

1992 Saturn SL2 (retired) - Elmo's Revenge -  Class B winner, Heroic Fix winner x2
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Re: ITB Wisdom

Hmm, Rusefi would make it easier to adjust everything.

https://www.facebook.com/greatglobsofoil/
This car....Is said to have a will of it's Own. Twisting its own body in rage...It accelerates on.
1978 Opel/Buick Isuzu(C>B>C>B) , 1996 Nissan Maxima OnlyFans (B) , Sold 1996 Ford Probe GT(B),

Re: ITB Wisdom

yup...I heard good things about RusEFI....once I make some progress with the build, perhaps that would be the next on the ToDo list....

MarioKart Driving School: 1987 Honda Prelude Si (Opus #28) 
Loudon, NH 2014 - Millville, NJ, Lightening 2019 (RIP)
New and improved: 1987 Honda Prelude Si (Opus #11) Pittsburgh, PA 2021 - ??
and finally won something, Class C Win: Loudon, NH 2022

Re: ITB Wisdom

My favorite Russian Collusion! Do it !!!!!!

Re: ITB Wisdom

Update:
I got the air fuel sensor/gauge (AEM Performance Electronics) installed, and it is reading very lean....
I'm not sure why though...so I'm trouble shooting....(?Temp sensor, MAP sensor, O2 sensor, Fuel Pressure regulator, Fuel filter and pump recently changed, etc.??)....scratching my head and losing my hair!
ECU is no help.  There is supposed to be a little window with a flashing light that indicates specific codes....but the ECU in the car does not seem to have one...).  Maybe I need to unscrew the cover and open it up?

and
I just got the injectors cleaned and tested
By Hurst Injector Service...nice, old timer guy in Fitchburg, Massachusetts, he's been doing this ....for a long...time....

https://hurstinjectorservice.com/

I recommend: quick turn around, $17 per injectors, plus $10 shipping....and he answers the phone/calls you back if you have any questions...
and he cleaned them well, and changed the little o ring gaskets and changed the tiny filters
certainly cheaper than replacing the injectors, and they look new!
Plus, he said if I need any other gaskets, etc for the fuel rail, filters, etc.  to call him, he has many spares (probably in little plastic bins in a shed outside his house, he has accumulated over the last 50 years....I should visit him next time I'm driving by....!)

I probably should have done this on the stock injectors....

So:
The motorcycle injectors came out to all approx. 255 cc/min

Stock are 235 cc/min, so I think I should be ok

Next:
I'm off to America's Largest Motorcycle salvage yard!  in New Hampshire

http://www.argocycles.com/vehicles/all/Automobile

for some electrical connectors.

Throttle cable just came in via EBay too!

(If we pull this off, its gonna be epic....)

(all suggestions, thoughts, recommendations, constructive criticism,  words of wisdom are appreciated!)

MarioKart Driving School: 1987 Honda Prelude Si (Opus #28) 
Loudon, NH 2014 - Millville, NJ, Lightening 2019 (RIP)
New and improved: 1987 Honda Prelude Si (Opus #11) Pittsburgh, PA 2021 - ??
and finally won something, Class C Win: Loudon, NH 2022

Re: ITB Wisdom

Man, I love when Lemons teams work for years to get the most out of their cars. It's been really gratifying to watch you work with a pretty mediocre car (actually a couple of them), getting nowhere near the Top 25 for years and then putting it all together in October.

It would be easy to move on from the Prelude or even change nothing; I'm so glad you're making an evolution of it.

Eric Rood
Everything Bagel, 24 Hours of Lemons
eric@24hoursoflemons.com

Re: ITB Wisdom

therood wrote:

Man, I love when Lemons teams work for years to get the most out of their cars. It's been really gratifying to watch you work with a pretty mediocre car (actually a couple of them), getting nowhere near the Top 25 for years and then putting it all together in October.

It would be easy to move on from the Prelude or even change nothing; I'm so glad you're making an evolution of it.


Brapppp Brapppp big_smile

https://www.facebook.com/greatglobsofoil/
This car....Is said to have a will of it's Own. Twisting its own body in rage...It accelerates on.
1978 Opel/Buick Isuzu(C>B>C>B) , 1996 Nissan Maxima OnlyFans (B) , Sold 1996 Ford Probe GT(B),

Re: ITB Wisdom

Thanks!
Its been tough, since I am not much of a mechanic....but if you have a 1987 Honda Prelude, Si version, non carburetor, fuel infected version with the manual transmission....I could probably help you out...
I certainly could not have done this without the help of the Lemons community and friends....

Biggest bang for the buck:
--- Make it lighter....remove AC, heater core (windshield does not fog up, I have a fan hooked up, works fine), remove power steering, and strip as much as possible (and I need to lose some weight too...)...car now weighs approx. 2100 lbs
----Upgrade to Accord hubs (with bigger brake rotors, calipers, axles. etc.) ; the wheels kept breaking off on sharp turns, literally the wheel/tire would snap off;
----keep it cool, add big radiator and keep radiator fan going all the time.  Car never overheats, even in the hottest weather....and I have never changed a head gasket, 6+years of racing)
----and other little stuff we've done over the years...probably adds up...but still more to go...!

so next in the evolution, hopefully for the NJ race:
ITB and
permanent full, complete, brake booster delete, probably Prius master cylinder, etc. in the plan, need adapters, etc.
I loved the feel of going boost-less....on another car, Probe,, and by just plugging the booster vacuum on the Prelude

MarioKart Driving School: 1987 Honda Prelude Si (Opus #28) 
Loudon, NH 2014 - Millville, NJ, Lightening 2019 (RIP)
New and improved: 1987 Honda Prelude Si (Opus #11) Pittsburgh, PA 2021 - ??
and finally won something, Class C Win: Loudon, NH 2022

Re: ITB Wisdom

And for all you Miata ....Miata-be-faster ....Lemons teams
MIATA ITBs!!!

I have a 2002 Mazda Miata (I barely fit in, but my kids like to drive) and its too nice to Lemonize...

I came across a youtube video of a guy that used Honda CBR1000 throttle bodies as ITB on a NB Miata , his may have been from a 2008  Honda CBR....so might be a bit different?  from my 2005 Honda CBR...?
Looks like he did a lot of work, but kind of long winded video

He uses carbon fiber nylon to 3d print.
Maybe some info here we could use for Prelude???
and maybe I should do this on my Miata after we are done with the Prelude???

https://www.youtube.com/watch?v=3ZxlchEByos
 
Plus he has a link to plans to 3d print adapters, etc. here with all the parts and basic instruction to install, etc.

https://www.youtube.com/watch?v=JinDuk-EiSA

what could go wrong???

MarioKart Driving School: 1987 Honda Prelude Si (Opus #28) 
Loudon, NH 2014 - Millville, NJ, Lightening 2019 (RIP)
New and improved: 1987 Honda Prelude Si (Opus #11) Pittsburgh, PA 2021 - ??
and finally won something, Class C Win: Loudon, NH 2022