Honda D Series Forum banner

1 - 6 of 6 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter #1 (Edited by Moderator)
Hey guys, new to the forum and new to tuning. I'm having trouble understanding how you know or find which kind of torque curve/how quick the ignition increase should be on a boosted engine. Ive got a built bottom end, stock head y8 with a hx35. ive made a base map in crome, but unable to post pictures cause my post count. My base timing is set to 12 degrees and advancing to 30 degrees (heard its a safe amount to begin with) i'll be running e85. The whole map I have made seems to be increasing in the 2d map, however I am pulling 1.5 degrees timing, per lb of boost. Getting down to 10 degrees at full boost (10 psi for now) at max rpm. Would looking at a compressor map of the turbo and finding out boost pressures at certain rpms help with finding how the curve should look?


I guess what I'm asking is, would I want to be at 30 degrees at 0vac just getting into boost. Then begging to retard? Or go into boost with say, 20 degrees and retard to 10?


I guess what I'm asking is, would I want to be at 30 degrees at 0vac just getting into boost. Then beginning to retard? Or go into boost with say, 20 degrees and retard to 10?
 

·
BATSLOMAN GIVES NO FUCKS.
Joined
·
4,099 Posts
this is not facebook. there is no need to repeat yourself every hour. just like the dmv, take a number, find a seat, and wait till the next available associate is able to assist you.
 

·
Meat Popsicle
91 CRX Si
Joined
·
2,936 Posts
You get a stock map, you populate the boost columns with some "best guess" formula like -1.5 degree/lb boost and x% fuel enrichment.

Then you use a det can and listen for signs of detonation. Add timing back in small increments until you hear detonation and pull it back 2 degrees once you hear it.

On the dyno, adding timing will show obvious changes in the torque curve until you reach MBT. When you're close to MBT, you'll notice that adding timing has less of an effect than it did before.

You need a det can
 

·
Registered
Joined
·
2 Posts
Discussion Starter #5
I get that finding the proper mbt must be found on the dyno. And yes the det can or some sort of knock detection system is needed. But I see dyno graphs climbing really aggressively almost like a 70 degree angle then going really linear at like 3.0 rpm (assuming that's where the mbt is) eventually dropping off obviously. And others more conservatively like a 45 degree angle and not getting to "mbt" which looks like until about 5.5rpm. How do I figure out the curve I'm looking for? Is a VE map needed? Does crome have a VE map?
 

·
Registered
P06/Neptune-Mr2
Joined
·
1 Posts
The torque curve that a particular setup requires, or produces, is dependent on many factors, the turbo being one of the largest contributors. Each setup will have its own unique requirements. The right torque curve is like the golden nugget of tuning.

One of the best tuning tools, with regards to knock, is the J&S Knockgaurd system. It can detect the onset of knock, or inaudible knock, before we can usually hear it with a detcan. Setting it up for sensitivity can be a challenge, but once you have eliminated engine noise (false knock), it works very well. It also has a headphone out. I actually listen to my engine on my stereo system (I EQ'd out the extraneous noise, and just have the narrow freq range that my engine [cylinder bore diameter] will ring at... around 6550 RPM for a 2.2L).

Do you have a knock sensor?

Anyways, the J&S allows you to find out, even with driving on the street and datalogging, what knock you are getting and where. Then you can review it at home, make some changes pulling timing out or adding it in etc, and go for another drive. A crucial area of the map will be where the turbo will like to spool. Looking at other dyno results from other similar setups should show you at what RPM the turbo is spooling.

Some general guidelines;
-get you AFRS dialled in so that you are perhaps 6-8% on the rich side of your target AFRS (probably around 11's or so)
-once your turbo hits max boost, your car should have decent acceleration. Does your boost climb slowly to 10 psi, or does it snap up to it?
-if the turbo is spooling quickly, but acceleration is sluggish but smooth, you could likely use some more timing in that RPM range.
-if you are getting no knock, and the car is sluggish overall, you can add say a degree of timing across the whole map starting from about 2000 RPM and up from there. See how the car and the J&S responds. If still no knock, but the car felt a bit bit better, do the same thing again. By incremental changes, you can introduce more timing without putting your car deep into a knock situation.
-once you have a general idea of what your ignition curve looks like, the dyno can help you tweak smaller power gains, smooth out holes and gaps in the power.
-you may find, depending on what type of dyno, and how it is set up, that you can run more timing on the dyno than you can on the street. Use the dyno as a tool to tweak things, but keep your street map as a reference for where you are getting knock on the street especially in the area of peak torque. You will have to return to that general timing range that your setup is happy with on the street, while employing a few tweaks that the dyno revealed (say perhaps you find you could add a degree or two above 6500 RPM without knocking, but was difficult to feel on the ol' seat-of-the-pants).

This way you can do most of the tuning yourself, and not have to fork out for more than a few hours on the dyno.

No I don't sell J&S etc, I just believe that it saves engines and is the best street-tuning ignition curve tool. Enjoy the tuning, it is an exciting time. And best of luck.
 
1 - 6 of 6 Posts
Top