12 replies to this topic

[regularguy]

now that it is finished, i figured it would be nice to share my experience getting a set of itbs running properly.  i know that there are not very many people that want to fight the ever so steep uphill battle with the ew engine with swaps being fairly easy and instantly gratifying.  i like my stock engine, and have spend enough time and money on it that going for a swap was not really high on the list.  going with the road less traveled and surprising fellow auto enthusiasts/ autocross competitors with a 30 year old engine holding its own is much more fun to me.  i had to make a push during our off season, and by taking my time and gathering everything needed before starting on the car itself, things proceeded smoothly and all unknown variables did not prove to be show stoppers-

 

this was the car as it started, definitely not a show car but perfect for its intended autocrossing duties:

 

sousa speed kindly gave me a good deal on an initial buy of his distributor adapter plate

a new obd1 distributor was acquired for really cheap on ebay, and then a rywire harness was sourced for integration of the engine to a newer obd1 ecu and hondata s300:

and lastly, a set of used itbs from a cbr954rr:

these were selected mostly because the tps is standard honda.  as it turns out, the outer wires on the plug have to be swapped, but it is definitely the easiest way to get a proper tps signal to the ecu.  

 

injectors turned out to be around 240-260cc and use an injector dynamics 2000cc plug, so the stock 954 ones stayed put with the aid of injector adapters sourced from rywire.  if the oem harness is included with the itbs (as pictured), it would be easy and much cheaper to just splice them in to whatever harness was being used.  the throttle cable cam will work with the crx throttle cable, although the mount on the itbs will have to be slightly enlarged to hold the throttle cable and the cable itself had to be shortened.  that was no problem, and i used an aluminum ferrule as a new stop a few inches up from the end of the cable.

 

the only thing that had to be farmed out was the runners for the stock manifold.  i used a stock lower half that was cut and had a set of aluminum pipes welded on.  the pipes were readily available on ebay as radiator hose extensions, and came with rolled ends as a bonus-

spacing on the middle two runners was just about perfect, but the outer two were slightly further apart (about 10mm more if i remember correctly).  as the stock 954 rubber boots were angled, i was able to spin them outwards and get everything to line up well enough.  it goes without saying that everything should be set on the itb side before the pipes are tacked onto the oem flange.  my welder was also kind enough to seal up the original injector bosses-  flow is not optimal of course with the void inside the manifold, but i was willing to accept whatever negative issues came of it.  

 

having situated the most daunting portion of the project, i was able to estimate that the fuel line fittings would work from both vehicles, and vacuum would also not be much of an issue with a cheap block to feed the booster.  the stacks from the 954 fit perfectly (of course), but a set from a 04-05 cbr1000rr also worked and were both shorter and more symmetrical.  airbox design was apparently drastically different and i went with the shorter stacks for a tidier appearance and zero chance of interference with the booster under heavy engine movement.  any high rpm power gains or low rpm losses were not really considered with the stack choices; i do plan on trying the longer set later if i get curious enough.

 

having an obd1 ecu required a speed signal, so an hf speedo was swapped and wired as it has been done so many times before.  i cant say there is a more elegant solution especially since the clusters are getting harder to find, but luckily i was able to find the required pieces and when i got the car on the road for the first time, the speed signal was pretty much spot on with the cluster.

 

installation of the harness was fairly straightforward, with a bit of wiring needed, and once the proper orientation of the distributor key adapter/extension was determined, it too fell in line quite nicely.  the 954 cold start thermo setup was left in place and plumbed, and it helps quite a bit with warm ups and initial driveability.  

 

 

[regularguy]

everything else went together in a very straightforward fashion, and as a bonus now the car is devacced!  

 

 

as for power, i could only assume that the stock dual plate throttle body was choking even the stock engine-  once i installed what seemed to be a web hardweld cam and the header i currently have it really needed the distributor springs and safc that was running the car up until now.  the car was nice and lumpy but part throttle and the overall driving experience was very lacking.  it was a real eye opener the first time the car fired and settled into a very agreeable idle.  theres even an idle adjustment cable in perfect place to make adjustments a breeze-  the car runs fantastically now and makes a sound that would make miles davis himself envious-  110whp never sounded so good.  it could definitely be a daily driver now even with the local traffic being as horrible as it is.   

 

the dark blue plot is with just an intake, header, distributor springs and safc tuning.  the red plot is with the cam and an 86 integra ecu added.  light blue is as it sits now, and i couldnt be much happier with the overall experience and outcome.  i am willing to help out anyone that is looking to head in this direction with their build-  there was not very much information readily available which made diving in a bit uneasy.  

[GeezRX]

Excellent write up...thanks for posting it and keep us up to date on pros/cons for the long run.

 

Skip

[P-Tail]

looks great! also, what strut tower bar is that?

[regularguy]

thanks-  as for the bar, its a type r trunk bar that just so happened to fit the camber plates that were on the car.  im starting to address bracing on the car, mostly in the front, to help the car work better on track.

[mrlindeman]

Sorry to bump this thread so late. Great build! That rocks, but i have a question. How was the intake temperature sensor and the positive crank case vent dealt with on this one? These are both issues as well as the idle air control valve that I am dealing with  on a carbon fiber intake system I am designing although not so related. Sorry for the Hijack but I think the info would be helpful for the ITB build too. Thanks for any info. I once planned this as a project but got lost due to lack of info. This thread has re-inspired me for sure  

[regularguy]

IAT placement for ITB applications is not very critical tbh, just as long as it isn't sitting next to a considerably hotter or colder thing in the engine bay.  I was going to plumb it into one of the runners but ended up just tying it down between the number 2 and 3 horns.  if you look carefully in the picture above the dyno chart, you can see the tip and the one of the screw holes of a stock sensor.  in a naturally aspirated application, anywhere in the intake tract would work (think ek civic and its push in style IAT).

 

emissions is not an issue here in hawaii, so as a general rule of thumb i vent all pcv outlets to atmosphere.  clean manifolds are happy manifolds.  not to mention it would take quite a lot to get an open ITB setup past a sniffer, let alone a visual.  i would assume a one-off carbon manifold would be in the same category as well?  or are the cars so old they are exempt in your neck of the woods?   

 

as for an IACV, i tried plumbing an obd1 valve into the vacuum block on the firewall at first.  i then found out two things:  1-  there isnt enough flow to properly control idle through one vacuum line, as the valve is not fast enough or close enough to the runners to make it work properly.  2-  there is definitely enough flow through one vacuum line to make the idle unstable, and more importantly take all the vacuum away from the booster and make racing the car both unpleasant and unpredictable  (having no plenum to pull vacuum means there is very little to begin with).  i understand why people use unassisted brake systems, and if i spent enough time and money i could get it to work.  that being said, i like a short pedal that requires less effort as i am fighting the no power steering battle irregardless.  i contemplated a vacuum can to help the booster, but things seem to work well enough as is so it is not going to be changed anytime soon.  as a bonus, the MAP sensor can now see when the little amount of vacuum available is being drawn.  with a manifold sporting a plenum, you could probably get a decent idle mechanically with throttle plate adjustment assuming the weather stays roughly the same every time you drive the car.  i tapped one side of the valve to feed the vacuum block, so it should work if plumbed into a plenum as well.  if disabling the IACV is not an option, you could just leave it plugged in to avoid a code and work around it.  

TL;DR-  IACV is disabled in the hondata calibration, MAP is not needed for alpha-n tuning.  plumbing a valve isnt impossible but only worth the effort with a plenum.

 

if i had to do it again, i would consider a cheddas adapter plate and a y8 manifold.  supercharger would be nice as well, but i think the firewall would need a lot of massaging.  cheap ITB sets are over 500 so i wouldnt buy even the obx stuff.  no matter what combination it ends up being, obd1 is key.  must have.  dont skimp.  support souza speed.  second best money spent on the car ever, right after the teins-

[CSPCRX]

Well done. Had an twm itb system on one. It was a monster.

[mrlindeman]

Thanks so much for the info! That was exactly what I needed!. I think i might set the IACV on the carbon intake similar to the stock setup for driveability

[na-spirit]

Thank you for this! Amazing work! pm'd

[whittlebeast]

Here is what I did on my G1 CRX 3 valve 1488.

 

http://www.nbs-stl.c.../CRX Intake.jpg

 

http://www.nbs-stl.c.../CRX Engine.jpg

 

And the early dyno sheet pic.  That works out to about 142 hp on a set of rollers per the dyno operator.

 

http://www.nbs-stl.c... Dyno Graph.jpg

 

I am now going B18C Type R and will be going with the same ITBs.  I run Megasquirt MS3 in full sequential.

 

Andy

[azz187]

Very nice job bud 👍 can't wait to see the b18, still 146hp is very respectable. I'm hoping to put itbs on my b swap got twms just gotta get a hondata to run them atm I've just got the stock type r intake installed and a chipped p28

[whittlebeast]

How are you tuning that motor?  Do you have data logging capability?  I have a fair amount tuning experiance wit this sort of thin and my be able to help.

 

Andy