Sequential fuel Tuning using EGTs

stevieturbo · Post by **stevieturbo** » Sun Jun 20, 2010 5:34 pm

800 sounds quite hot at idle ??

I only have 2 EGT references. One in the header tube of cyl5, and one in cyl 8

One for the ecu for logging purposes ( wish it did 8 !! ) and one for a Gauge in car. ( If I get a Dashdaq, I may well go for two TC-4's and interface them all together. )

Anyways. At idle or cruise, mine would generally be around 550-600degC
Even at quite a lean cruise they wouldnt stray much over that. Although oddly the Greddy gauge, doesnt 100% match with the little 0-5v jobbie for logging.

My problem here is...how the heck do you calibrate test to see which is accurate at such high temps ?

As for the differences. It could be airflow due to intake design, injector flow, exhaust manifold flow, camshaft wear or valve clearances ( or lifter pre-load ? )
Hard to know really.

I'd think mostly intake design, then injector flow rates.

Despite the little Siemens injectors being very good. Mine were not linear when tested at 30%, 50% and 80%. I dont recall exact figures though.
That was two sets of shorty style and full size that I'm using for primaries and secondaries.

I mixed and matched pairs so that flow would be as even as possible at 50% DC on each cylinder. I set both injectors to come online at anything over 3000rpm so that hopefully when its making some power, each cylinder does get an even amount of fuel. ( Not running sequential due to having 16 injectors )

daxtojeiro · Post by **daxtojeiro** » Sun Jun 20, 2010 8:16 pm

Hi Steve,
I think it has to be intake and injectors as you say. The cam may be worn but likely to show issues at higher rpm I would have thought, but could all account to the total amount of trim needed.

Id love to have some readings off another RV8 to compare, Im off to the TVR Roar next weekend, will wonder around with my lazer temp reader and see what I can compare it to

Phil

stevieturbo · Post by **stevieturbo** » Sun Jun 20, 2010 8:29 pm

I guess at the end of the day does it matter why they are different ?

The fact is you can equalise them, which in theory should be a good thing.

Out of interest...what sort of temps are you seeing at WOT ?

Ive just been out raking about in mine tonight, and even a good hard run in 4th gear only sees it hitting 700degC in header 5.

AFR's would be low 11's ( with water/meth )

What sort of response time does a 3mm K type have ?

If I wasnt so lazy....I'd fit the TC-4 to mine. Just cant be be bothered taking the manifold off to weld bosses on !!!

Although it would be nice to test it against the wee thingy I use to convert to see if they do actually read the same.

conrod · Post by **conrod** » Sun Jun 20, 2010 8:41 pm

nice work! The differences are MOSTLY due to uneven air distribution from the stock inlet manifold, as well as the small variations between injector flow rates, variations in exhaust manifolds etc.

But you knew that anyway!

Conrad

daxtojeiro · Post by **daxtojeiro** » Mon Jun 21, 2010 9:35 am

The one thing Im intreaged with is that there is no pattern to it. I was expecting the inner and outter cylinders to be similar, but they are random. I've spoken to V8D and a lot could be down to the TVR heads as they are ported and opened up, could be the fact that they are all different due to being done by hand.

Anyhow, as you say, it doesnt matter.

Im getting 700C at idle at 15ish AFR, well I think its 15ish as one bank reads 16-16.5 and the other is reading 14-15, I think one or both of my LC1s need calibrating

I have yet to do any WOT measurements, I will do that during the week if the weather gets better.

Just as a note, I swapped all the EGTs around to ensure they were reading correctly, and last night I checked 2 on each bank to another 2 on each bank, and tuned all 8 to get them the same regardless of AFR.

Will let you all know when I get some WOT temps,
Phil

daxtojeiro · Post by **daxtojeiro** » Tue Jun 22, 2010 9:36 am

Hi all,

I've done some logging whilst driving now and it appears they all follow the same trim needed at idle, all apart from cy4 so far, that looks too rich and needs some trim removed. So thats going to be easy enough to tune, I wondered if they would alter individually all over the place with load / rpm, but thankfully they dont!

Peak EGT at WOT is around 800C, thats around 12.5AFR. I have seen 1000C in the logs, need to work out when that occured, but they sit around 700-900C for most of the time.
Phil

daxtojeiro · Post by **daxtojeiro** » Thu Jun 24, 2010 9:01 am

Hi all,
incase anyone wants to read up on what I found, etc, I've written it all up here:
http://www.extraefi.co.uk/EGT_Tuning.html
cheers
Phil

SuperV8 · Post by **SuperV8** » Thu Jun 24, 2010 12:16 pm

You must have very reasonable or deaf neighbours to do all this testing

, my neighbour threatened to burn down my garrage

stevieturbo · Post by **stevieturbo** » Sat Jun 26, 2010 5:27 pm

I still cant get my head around those high temperatures.
7-800degC at idle just sounds high ???

daxtojeiro · Post by **daxtojeiro** » Sun Jun 27, 2010 1:05 pm

stevieturbo wrote:I still cant get my head around those high temperatures.
7-800degC at idle just sounds high ???

Could be my sensors as they wernt designed to take that temperature, even though I dont think it would be the issue. I can soon try some others
Phil

conrod · Post by **conrod** » Mon Jun 28, 2010 9:40 am

stevieturbo wrote:I still cant get my head around those high temperatures.
7-800degC at idle just sounds high ???

agree, that would have the manifolds glowing at idle! I am thinking it is a sensor or calibration issue, you sure it is not 700-800 fahrenheit?

Interesting that the ports were hand ported, I was not aware of that, certainly could be part of the reason for the discrepancies between cylinders.
Conrad

daxtojeiro · Post by **daxtojeiro** » Mon Jun 28, 2010 1:48 pm

Out of interest, wouldnt the position of the sensor make a difference in the value?
Im 1" from the head in each exhaust, I will get some more sensors later

Phil

stevieturbo · Post by **stevieturbo** » Mon Jun 28, 2010 2:25 pm

daxtojeiro wrote:Out of interest, wouldnt the position of the sensor make a difference in the value?
Im 1" from the head in each exhaust, I will get some more sensors later
Phil

it would...but not that much. Mine are within 6" of the valve.

v8rob · Post by **v8rob** » Wed Jul 07, 2010 8:40 pm

phil those temps on idle are just wrong unless you are running it very retarded? on idle i would be looking for around 450.

daxtojeiro · Post by **daxtojeiro** » Thu Jul 08, 2010 8:53 pm

v8rob wrote:phil those temps on idle are just wrong unless you are running it very retarded? on idle i would be looking for around 450.

Hi Rob,
yeah, my sensors are not calibrated to the measuring unit, so all I'm really showing is that theres a difference between cylinders, not the actual temp. I will calibrate it soon, I just need to work out what my sensor outputs are, I borrowed them from work and cant find any info on them

Phil