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Meat Popsicle
91 CRX Si
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2,936 Posts
Discussion Starter #1 (Edited)
So after 10 years of building this thing, I finally have a dyno session scheduled for next Thursday.



I feel pretty good about the street tuning I've done up until this point but I want to make sure I'm not missing something simple, that my approach is sound, and hear any tips/tricks that may be helpful.

I'm already equipped with a wideband and the shop is going to use a tail-pipe wideband to for graphing purposes. I am using a det can for knock detection.

Since this is a supercharged engine, I'm expecting a pretty flat torque curve.

My plan is to do a base pull, identify any dips/spikes in the torque curve, and add/remove timing to flatten out the curve. Once the curve is relatively flat, I'll increase timing across the WOT cells in 2 degree increments until either:

a.) The 2* timing increases fail to show increases in the torque curve.
b.) Knock is heard over the det can.

I'll be adjusting the fuel map where necessary to accommodate for the timing changes.

I know my goal here is to identify MBT and then back the timing off slightly but:

Is this logic sound?

When should I advance/retard the cam gear? I assume this should be towards the end of the session.

Any other advice?


I'm open to all suggestions and criticism.

Thanks in advance!

-Patrick
 

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89 EF 4wd sedan
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505 Posts
I just had mine tuned last week, looks like i have a similar setup but DOHC. I didn't tune it myself, but i was speaking to my tuner about adjusting the cam gears and he basically said to do some research to see what works before playing around with them, because basically every time they're adjusted he has to go through all the fuel maps again before doing a power run and really seeing if the changes were beneficial or not.

I've been reading that a retarded intake event and low/no overlap is key which on SOHC is going to heavily rely on the lobe separation angle of your current cam selection.

Good luck mate! Looks neat.
 

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Meat Popsicle
91 CRX Si
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2,936 Posts
Discussion Starter #3 (Edited)
Thanks for the input.

Cam selection was difficult because I needed increased lift but finding something that increased the LSA was impossible. Since there are no A6 cam blanks produced, I had to select a regrind but I definitely did my research to find out which had the best lift increase with the least amount of overlap increase.

The way I understand it, with SOHC, retarding the cam timing shifts the powerband upwards and advancing it shifts it downwards. I don't plan on messing with it too much but I definitely want to take advantage of the option.
 

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89 EF 4wd sedan
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505 Posts
Thanks for the input.

Cam selection was difficult because I needed increased lift but finding something that reduced the LSA was impossible. Since there are no A6 cam blanks produced, I had to select a regrind but I definitely did my research to find out which had the best lift increase with the least amount of overlap increase.
Do you mean increased LSA? What cam did you end up going with?

The way I understand it, with SOHC, retarding the cam timing shifts the powerband upwards and advancing it shifts it downwards. I don't plan on messing with it too much but I definitely want to take advantage of the option.
For sure, be keen to hear what works for you!
 

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Meat Popsicle
91 CRX Si
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2,936 Posts
Discussion Starter #8
Tip to self. Don’t use 20+ year old DSM injectors, even if they’re cleaned and flowed.

Two injectors got stuck open, flooded two cylinders with fuel, now I’m working on getting a tow dolly to tow the car home. Sucks!
 

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89 EF 4wd sedan
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505 Posts
Tip to self. Don?t use 20+ year old DSM injectors, even if they?re cleaned and flowed.

Two injectors got stuck open, flooded two cylinders with fuel, now I?m working on getting a tow dolly to tow the car home. Sucks!
Damn, i don't think i've ever heard that happening before. How far into the tune were you?

Goodluck getting it sorted.
 

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Meat Popsicle
91 CRX Si
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2,936 Posts
Discussion Starter #10
Fourth pull. On top of the issue I experienced with fuel, the numbers I saw up until then were way lower than I expected. Basically only 30hp above what a typical JRSC kit produces on a D16 with bolt ons.





I know there’s a little more power to be made with the tune but there’s no way I’ll hit the 220whp mark that I was expecting.

Maybe the new injectors will help a little.
 

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89 EF 4wd sedan
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505 Posts
Hmm that doesn't seem too far off the mark. What were your IAT's like?

Me and a mate here in oz (Grifty on here) both just had our aftercooled JRSC tuned in the last couple of weeks. We both made around 165hp. Mine's a DOHC, ported head, cams, b18 valves forged pistons/rods, 3" pulley... tbh i was expecting more too, my goal was 200hp atw. As a comparison, I made 140hp on a stock motor with no cooling.

I realised last weekend though that the water pump for my heat exchanger was switching off after 10 seconds so the water wasn't circulating, so hoping to squeeze out a few more hp when i go back... But my expectations aren't high.
 

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Meat Popsicle
91 CRX Si
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2,936 Posts
Discussion Starter #12
IATS were ~103F at the beginning of the pull and ~133F by the end. The cooler did a good job of bringing the IATs back to just over 100F at the beginning of each run.

Perhaps my expectations were unrealistic but I certainly expected to see near 200whp.

When the new injectors and FPR get here I’ll bring it back to the dyno and finish the tune.

Hoping that retarding the cam will produce a few more top end HP and I’m sure there’s still a little to be gained from the tune although I’m pretty close to detonation in some areas.

What kinds of IATs were you seeing?
 

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89 EF 4wd sedan
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IATS were ~103F at the beginning of the pull and ~133F by the end. The cooler did a good job of bringing the IATs back to just over 100F at the beginning of each run.

Perhaps my expectations were unrealistic but I certainly expected to see near 200whp.

When the new injectors and FPR get here I’ll bring it back to the dyno and finish the tune.

Hoping that retarding the cam will produce a few more top end HP and I’m sure there’s still a little to be gained from the tune although I’m pretty close to detonation in some areas.

What kinds of IATs were you seeing?
I'm hoping the same thing with the cam timing, we didn't play with it at all in the first dyno sesh.

I still need to grab the datalog off the laptop from the guy who tuned it for me. Should get it soon actually, will report back.
 
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