Performing Honda K24a3/AST5 6spd Conversion

lookforjoe

True Classic
#10 hose fractured during the spirited driving up in Ithaca...

PXL_20210627_212654114.jpg


...got a little cooked as a result

205658764_10220288853076285_3962333291717388402_n.jpg


Also killed a large bluebottle

PXL_20210627_162421345.jpg
PXL_20210627_162418229.jpg


packing the car for the drive, show & hiking

PXL_20210627_144526066.jpg


PXL_20210627_144140838.jpg
 

lookforjoe

True Classic
It would seem that attaching the body of the hose to the engine would reduce the fracturing at that point, the compliance would need to come from the vertical section of the flex hose.
The cause would seem to be the excessive rigidity of the #10 hose - and it's a short run, so not much flex going on there - so, the fitting is taking the brunt of it. I've ordered a couple of alternate fittings for that location. I have an earlier iteration hose I made that coupled with a 90º elbow off the compressor, that setup was a much sturdier layout - I removed it because I thought the loop style fitting was more 'relaxed' in terms of stress on the line/fitting. Not sure if there is any practical way to brace the line fitting to the manifold at that point.

The specific line fitting that fractured is undersized in terms of the tube ID - not sure why & I didn't pay attention to it at the time. I also tightened the arc a touch when I installed it to keep the hose section from pressing on the bulkhead, so likely as not I induced the fracture by doing that. I was driving very aggressively on a bunch of the winding roads up there, with much harder high rpm shifts than I have ever previously driven, so likely the drivetrain was torqued more aggressively than in the previous 2K miles. That hose/fitting I revised quite some time ago (in the relative scheme of things). This area seems to be the worst in terms of issues. It does seem like I have finally conquered the AC compressor mount issue though - the latest support held up over the 500 miles with no issue - that would however put more load on the lines since the compressor mount was no longer 'flexible" 🤪

Perhaps I need to redo the line with reduced barrier #10 - that would give much more flex in the hose portion, however the fitting to the accumulator is a custom #10-#12 step (no production version), which was a PITA to weld the first (2x) time around - so I really don't want to have to redo that...

IMG-20200316-141649.jpg
 

lookforjoe

True Classic
Being a little impatient, I decided to try to fix the AC line - I got it welded OK, but the heat killed the hose/crimp...

PXL_20210628_183416061.jpg


Wouldn't hold vacuum. Took two other fittings & made one - cut off the beadlock & welded on the MOR fitting from the one shown below

PXL_20210627_215232848.jpg


Combined that with the earlier iteration hose I had made for the low side (didn't care for it as it sits up against the bulk head - however it has more length & more give. It held vacuum & charged just fine, so we'll see how it goes. I still have new fittings on order so I can make an alternate as needed later one. Just want to make sure I have working AC for the drive to MWB Open House next month

PXL_20210628_183430784.jpg


Back to the idle issue... on the drive home we hit two 30-40min delay zones - crawling, on off gas, and the throttle decided to act up on the 2nd crawl - won't drop below 2K when coming to a stop - most annoying. The car didn't overheat at all though -stayed right at around 200 stationary & dropped once moving. What I did when we got home was to remove thew TB & reset the bobbin tension to a stiffer setting - I assumed the bobbin tension at rest was not countering the pre-load spring in the TPS, and hanging up - sometimes.... Anyway, when I drove it this morning, is seemed better - but then it hung again. Fiddling around the TB & TPS, I found that if I jiggled the TPS connector just so, I could make the IACV surge. I had bought a generic TPS pigtail back when I went through all the TPS nonsense last year. I removed it & replaced with a high quality Sumitomo connector housing & terminals (HX 040 series)

removing pigtail & terminals

PXL_20210628_200145220.jpg


crappy ones
PXL_20210628_201940537.jpg


recrimp with new termnials
PXL_20210628_201908239.jpg


Seems better, at least it hasn't hung up once in the various drives I took this afternoon. Time will tell on this one.
 

kmead

Glutton for punishment
I had forgotten about your receiver being right there and not allowing any forward back motion. You have packaged an amazing amount of stuff in next to no room. :)
 

ng_randolph

Bjorn H
Being a little impatient, I decided to try to fix the AC line - I got it welded OK, but the heat killed the hose/crimp...

View attachment 48899

Wouldn't hold vacuum. Took two other fittings & made one - cut off the beadlock & welded on the MOR fitting from the one shown below

View attachment 48904

Combined that with the earlier iteration hose I had made for the low side (didn't care for it as it sits up against the bulk head - however it has more length & more give. It held vacuum & charged just fine, so we'll see how it goes. I still have new fittings on order so I can make an alternate as needed later one. Just want to make sure I have working AC for the drive to MWB Open House next month

View attachment 48900

Back to the idle issue... on the drive home we hit two 30-40min delay zones - crawling, on off gas, and the throttle decided to act up on the 2nd crawl - won't drop below 2K when coming to a stop - most annoying. The car didn't overheat at all though -stayed right at around 200 stationary & dropped once moving. What I did when we got home was to remove thew TB & reset the bobbin tension to a stiffer setting - I assumed the bobbin tension at rest was not countering the pre-load spring in the TPS, and hanging up - sometimes.... Anyway, when I drove it this morning, is seemed better - but then it hung again. Fiddling around the TB & TPS, I found that if I jiggled the TPS connector just so, I could make the IACV surge. I had bought a generic TPS pigtail back when I went through all the TPS nonsense last year. I removed it & replaced with a high quality Sumitomo connector housing & terminals (HX 040 series)

removing pigtail & terminals

View attachment 48901

crappy ones
View attachment 48903

recrimp with new termnials
View attachment 48902

Seems better, at least it hasn't hung up once in the various drives I took this afternoon. Time will tell on this one.
I am wondering if you would be better off running the U's as hose rather than hard line. Hose has virtually no longitudinal flexibility, so your short straight hose runs might be stressing the hard lines.
 

kmead

Glutton for punishment
I am wondering if you would be better off running the U's as hose rather than hard line. Hose has virtually no longitudinal flexibility, so your short straight hose runs might be stressing the hard lines.
To your point, getting so some flexibility somewhere is likely to be key. The forward aft motion of the engine with little compliance in the flex hoses from the fixed transitions the flex is going to happen somewhere.

With 20/20 rear view perhaps running the AC lines to the left side of the compartment would have been better for the lines but with all the intake etc likely not possible.

Getting some generous radii would give some of that. Actually having the hard bend transitions isolated from the compressor with flex hose on either end would help a lot in that regard.
 

lookforjoe

True Classic
I am wondering if you would be better off running the U's as hose rather than hard line. Hose has virtually no longitudinal flexibility, so your short straight hose runs might be stressing the hard lines.
To your point, getting so some flexibility somewhere is likely to be key. The forward aft motion of the engine with little compliance in the flex hoses from the fixed transitions the flex is going to happen somewhere.

With 20/20 rear view perhaps running the AC lines to the left side of the compartment would have been better for the lines but with all the intake etc likely not possible.

Getting some generous radii would give some of that. Actually having the hard bend transitions isolated from the compressor with flex hose on either end would help a lot in that regard.

That routing would be a last resort - the length of #10 barrier hose that would be needed to get a gentle curve back to the compressor posts would require the line to run in a giant "crook" pretty much over the entire engine (at least). I can't deal with the bay looking like a giant AC hose collection 🤪 . Have to see how this holds up in use.

I really need to get the oil consumption addressed - I used a quart in 200 highway miles(!). I'm wondering if the fully closed throttle (Larger TB won't set base idle unless TB is essentially closed on these) is causing excessive CC draw. I didn't have this issue originally, with higher idle/ TB not fully closed, even with the bad HG, unless I'm misremembering. I'm going to try eliminating the PCV as a test. Also need to do another leak down & compression test to compare with previous numbers, and check spark plug wear / oil comtamination.
 

kmead

Glutton for punishment
That routing would be a last resort - the length of #10 barrier hose that would be needed to get a gentle curve back to the compressor posts would require the line to run in a giant "crook" pretty much over the entire engine (at least). I can't deal with the bay looking like a giant AC hose collection 🤪 . Have to see how this holds up in use.

I really need to get the oil consumption addressed - I used a quart in 200 highway miles(!). I'm wondering if the fully closed throttle (Larger TB won't set base idle unless TB is essentially closed on these) is causing excessive CC draw. I didn't have this issue originally, with higher idle/ TB not fully closed, even with the bad HG, unless I'm misremembering. I'm going to try eliminating the PCV as a test. Also need to do another leak down & compression test to compare with previous numbers, and check spark plug wear / oil comtamination.

I was thinking a few inches of flex from the compressor to the hard bends and then back to the flex you have, so a few inches longer over the intake side. The rigid connection is likely what is killing the bend parts.

Going aback and reading my note the last line was where I sort of intimated this. I wasn’t clear as I roamed across the possible solutions.
 

lookforjoe

True Classic
I was thinking a few inches of flex from the compressor to the hard bends and then back to the flex you have, so a few inches longer over the intake side. The rigid connection is likely what is killing the bend parts.

Going aback and reading my note the last line was where I sort of intimated this. I wasn’t clear as I roamed across the possible solutions.

Even that means more than a few inches - the beadlock fittings that have to attach to any flex hose are each 3-4" minimum, if not more - that still puts any such flex section around 9-12" over the intake/ TB area, really not practical.
 

lookforjoe

True Classic
The new low side AC line fitting has held up so far, however the fitting nut came loose when driving hard. I added a line clamp to keep the hose from see-sawing. Tucked down on the left rear, before the beadlock crimp

PXL_20210717_002359908.jpg
 

kmead

Glutton for punishment
Sorry an aside question, what brand of vacuum pump do you have? It looks like I need to learn a new part of the trade on one of my Honda’s.

Many thanks.
 

lookforjoe

True Classic
Yesterday morning I added a duct to feed air up to the oil pan - we'll see if it makes any difference to oil temps. I also added some heat wrap to the WBO2 sensor harness - it was hitting the downpipe at some point. I secured it further to hopefully prevent contact.

chopped up floor heater duct I had saved from the S40 parts car
PXL_20210720_161809017.jpg



PXL_20210720_161840987.jpg


PXL_20210720_161905456.jpg


PXL_20210720_161911763.jpg


PXL_20210720_161822290.jpg


Spent yesterday & today up in the Harrimans - had a little campfire last night

PXL_20210721_012202063.jpg


and at Storm King Art Center - couple of the pieces

PXL_20210721_164041939.jpg


PXL_20210721_160338627.jpg


This was on my C30 when I got home this evening

PXL_20210721_195139551.jpg
 
Top