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Arouse the DAMPFHAMMER!
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...so it is based on engine temp at the coolant outlet, not the temp about 3 metres away from the engine :D
...and after the radiator, when it was already cooled down. The average of 200 °F might be better lowered too.

KTuner can do DBW, however I got rid of that TB, and I don't want to fit a DBW pedal assembly..
You don't like it for what reason? Clearance again or tuning it?
 

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Discussion Starter #22
...and after the radiator, when it was already cooled down. The average of 200 °F might be better lowered too.

You don't like it for what reason? Clearance again or tuning it?
Yes, I'm sure I'm loosing performance with that high a coolant temp - I'm assuming normal range is closer to 185-190 - I think the factory T/stat was either 182 or 187ºF...

I didn't even consider using the DBW - the stock throttle pedal pivots from the base, I didn't even look at if there were anyway to mount a DBW throttle pedal assy, I don't have any room above the pedal.



 

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when I had a 70mm TB, the car would cruise around 1% TPS and had this jerkiness about the transition from idle to running. Even reducing the MAP treshholds for idle to running would not change that.
I spoke with Christian Dohner, the guy behind my Doctronic ECU. He told me that there are some additional thresholds outside of the parameters you can set at least in his product. The parameters you show also editable there as far as I can glance first look. Also even the smallest air lead around the TB make idle troublesome. The OE TB have a sealant around the throttle blade edges for this reason. At some point the S90 TB starting being stick. I ditched it and fitted a J’s racing 64.5mm TB based on the OE one, but had to reapply a sealant as otherwise, idle would not come down. If you could see any light passing the edges of the blade holding the closed TB into the sun, it would not idle. Once this was fixed with a special OKS low friction paint, it idled fine. I then added a Aquity TPS and the throttle responce became even more like a stock engine. I did a compression of MAP over WOT runs with the 70mm TB vs the 64.5mm TB and the pressure difference was on the order of a few mbar, so <0.5% or 1HP for a build K22 stroker with Toda A3 cams. These differences were essential in the noise. But drivability with that OE based TB is miles ahead of the big 70mm TB.
 

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Discussion Starter #24
Thank you for your input!

I installed the 72mm TB, and with the correct (RSX Type S) TPS, I was able to properly set the base setting to 0% in software @ idle, with the % value increasing as soon as the throttle is cracked open. I have driven it about 50 miles in mixed town/highway driving, and the issue I had is gone. I made a reducer for the MAP orifice that I made - LotusElise pointed out that it really needs to be >2mm . I haven't done any logs yet to see what MAP values are presented under load/WOT conditions.



My main issue now is the operating temp, which is too high. I'm pretty sure I have a head gasket issue - I didn't use a OEM gasket - I have a slight coolant smell at the exhaust when starting cold, and I keep getting air in the cooling system (I have no external leaks that would also suck air in). I'm not driving it hard until I take care of the head gasket.
 

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A possible issue with the overheating could be due to coolant diverter, head gasket and what cylinder head is being used. Katman has a handy guide to reference. K20 Head Swap onto K24 Block – .:FFS TechNet:.


When swapping a K20A (EP3/DC5), K20A2, or K20Z1 head onto a K24A1/A2/A4 block the following parts are required:

  • CRV / K24A1 head gasket – Honda P/N 12251-PPA-004
    This gasket matches a K24A’s 87mm bore size  and also shares the same exact coolant passages as a Type-S head gasket + head. You can’t/don’t want to use K20A2/Z1 headgasket because it has a smaller 86mm bore size and the gasket will hang into the cylinder bore.
  • Remove coolant diverter – if present
    If left in place, may cause overheating issues (says the internet). The PRB head isn’t designed nor requires the use of a coolant diverter.
  • Use K24A headstuds
  • Use K24A timing chain

When swapping an RSP or K20Z3 head onto a K24A1/A2/A4 block the following parts are required:


  • TSX / K24A2 headgasket – Acura P/N 12251-RBB-004
    This gasket matches the K24A 87mm bore size and has the proper coolant passages for the RSP, K20Z3, and K24A2 heads.
  • Coolant diverter MUST be used
  • Use K24A headstuds
  • Use K24A timing chain

An easy rule of thumb is that a head gasket matches the head its designed to work with.
 

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Arouse the DAMPFHAMMER!
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...LotusElise pointed out that it really needs to be >2mm . I haven't done any logs yet to see what MAP values are presented under load/WOT conditions.
It was 1 mm which I suggested.

Good to read you sorted the engine speed jumping issue out!

A possible issue with the overheating could be due to coolant diverter, head gasket and what cylinder head is being used. Katman has a handy guide to reference. K20 Head Swap onto K24 Block – .:FFS TechNet:.
Good point 🆙
 

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The Fiat fan temp sensor is on the outlet of the radiator. I need to rewire the circuit to use the fan control built in to the EMS, so it is based on engine temp at the coolant outlet, not the temp about 3 metres away from the engine :D




KTuner can do DBW, however I got rid of that TB, and I don't want to fit a DBW pedal assembly.. I'm also hoping this is more stable than the larger TB & TPS setup I have now.
Do you have room to tap in a water temp sensor to the intake manifold like so,? I’ve been told this is the most reliable spot for measuring true coolant/engine temperature for the gauge cluster.
92B08229-25E7-43C1-9BC4-A31D89123645.png
 

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Discussion Starter #29
Thank you for the suggestion - however I removed all the water passages from the K24 runners.



I put my gauge sender in the water outlet (top left)

 

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Discussion Starter #30 (Edited)
A possible issue with the overheating could be due to coolant diverter, head gasket and what cylinder head is being used. Katman has a handy guide to reference. K20 Head Swap onto K24 Block – .:FFS TechNet:.
Mine is all K24 - block & head original to motor. What is the coolant diverter - I can't find reference to that (never mind, I hadn't read far enough to see it mentioned. Not applicable since I'm using stock combo. There is definitely coolant coming out the tailpipe. I reduced the pressure of the cap, which helped until I get the head off.

Unless there is something else about the motor I don't know about that could push coolant into the cylinders besides a head/gasket issue?
 

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The side housing where you have the upper radiator hose could leak down coolant to the egr port. As cheap as those gaskets are I would check that before pulling the head.
 

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Discussion Starter #32
The side housing where you have the upper radiator hose could leak down coolant to the egr port. As cheap as those gaskets are I would check that before pulling the head.
Good thinking! I did however tap that and close it off with a NPT plug. Like the intake runners, I got rid of every unnecessary (potential) water passage

 

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Yes, unfortunately that is my conclusion.
Maybe leak down test before pulling the motor out ? I’m assuming it needs to come out for almost anything it looks like it’s tucked very snug in that engine bay. But if you’re sure it’s burning coolant , might not be worth the effort.
 

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Discussion Starter #36
Maybe leak down test before pulling the motor out ? I’m assuming it needs to come out for almost anything it looks like it’s tucked very snug in that engine bay. But if you’re sure it’s burning coolant , might not be worth the effort.
Yeah - when I start it cold you can smell & see the coolant out the exhaust. I reduced it by modding the coolant pressure cap so it doesn't build more than about 5 psi system pressure. Since I'm running Evans Waterless, little or no pressure is not a problem.
 

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Did you have any issues when you tightened the head bolts after replacing the head gasket the first time? I think it's like 56 lb ft and then a couple 90° increments.
 

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Discussion Starter #38
Did you have any issues when you tightened the head bolts after replacing the head gasket the first time? I think it's like 56 lb ft and then a couple 90° increments.
I just followed the torque spec in the manual for used bolts. This time, I'm using new bolts, which specifies an additional 90 degree
 

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Discussion Starter #39
Maybe leak down test before pulling the motor out ? I’m assuming it needs to come out for almost anything it looks like it’s tucked very snug in that engine bay. But if you’re sure it’s burning coolant , might not be worth the effort.
I'm going to do a leak down test in the next couple days - there is a significant coolant flow issue - just running it at idle the t/stat hose is not heating up, and the radiator is also cool on the output side. If I bleed the rad, I can get the temp up at the t/stat, but, if I keep it running the hose cools off again. I can only assume whatever blowby I have is creating air pockets, and inhibiting proper flow. I've personally never experienced it like this though.

I did pull the t/stat & swap it for another, it made no difference. I was also wondering if the water pump impellers fail on these motors - Just trying to cover every possible aspect that would screw with the circulation.



The only other question would be regarding the K-Tuned water outlet on the side of the head - I don't know if that could be an issue, raising the head temps

 

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How are you bleeding air out of the head? Obviously with with coolant lines running downward, air locks will be very difficult to bleed normally

N/m i see your header tank above the outlet with the factory bleed circuit.
 
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