Craigs New Datsun Sunny
- Thread starter craiGTi
- Start date
shaggy_master
brapp brapp!
This is why I was concerned about Jez mapping N/A motors...
I'm no engine tuner lol... but from what I can understand, on high comp motors you typically run normal base ignition timing (15* +/- 2*) then control the Detonation with the timing map... obviously keeping it conservative where needs be ??
Thats how I've always visualised it anyway.
I would say having your base Ingition timing set to 4* is fucking up the whole thing... like at the recent RR day... Rich's car gained 12hp from a minor tweak, and nearly 30hp from a proper 17.5* timing advance...
So who knows? Maybe the Turbo cars Jez is used to mapping just require shit loads of fuel and not much timing map adjustments?
Cos after all... The timing map is where the power comes from when N/A mapping
Hard Luck Craigybaby.. I just hope it gets sorted so you're happy man.
I don't think the comp's too high either BTW... I do however think the short duration of the N1 cams is too short for the C/R though, but thats another matter.
Joe
Thats why i will be going to someone like gtart to get mine mapped with a dastek.
What about Ed ad fusion motorsports?
This is why I was concerned about Jez mapping N/A motors...
I'm no engine tuner lol... but from what I can understand, on high comp motors you typically run normal base ignition timing (15* +/- 2*) then control the Detonation with the timing map... obviously keeping it conservative where needs be ??
Thats how I've always visualised it anyway.
I would say having your base Ingition timing set to 4* is fucking up the whole thing... like at the recent RR day... Rich's car gained 12hp from a minor tweak, and nearly 30hp from a proper 17.5* timing advance...
So who knows? Maybe the Turbo cars Jez is used to mapping just require shit loads of fuel and not much timing map adjustments?
Cos after all... The timing map is where the power comes from when N/A mapping
Hard Luck Craigybaby.. I just hope it gets sorted so you're happy man.
I don't think the comp's too high either BTW... I do however think the short duration of the N1 cams is too short for the C/R though, but thats another matter.
Joe
i agree on the timing thing, i've e-mailed jez asking for more info on exactly what was done, loads ofpower to be lost if it was the base timing all backed off that low
don't agree withthen1 cam/high comp thing though, i know where you're comin from but countless builds in the USprove n1 cams make awesome results. i did nearly get some 2nd hand kelfords a while back but they're relatively untested and by the sound of it need at least springs, retainers and possibly an aftermarket intake mani to make them work properly - and i just haven't got the cash for all those extras
first job is to sort this clutch release bearing thing, then the valve stem seals. after that i'll sort the rest out. it's still pretty damn quick as it is - waaayyyy wayyyy quicker than my stripped, fully bolted on n15 gti was so not too shabby
http://www.team-integra.net/forum/display_topic_threads.asp?ForumID=10&TopicID=27552&PageMsg=Viewing+Common+Topic
Just had a read of this honda thread ^^, which talks about moving the powerband up the rev range with cam gears, if i want to do the opposite then as my powerband seems most potent between 7k and the 8k limit i need to do the reverse.
It mentions tightenting the cam lobe seperation angle which in turn increases overlap, so i therefore need to widen the lobe seperation angle therefore decreasing overlap. I'm presuming to do this i need to retard my intake cam and advance my exhaust cam?
that sound about right?
obvioulsy this is best done on a dyno for the optimal results but the principle is correct yes?
other sideeffects according to the honda thread of widening the lobe seperation angle will be..
- decreased cylinder pressure
- decreased chance of engine knock
- decreased cranking compression and therefore 'effective' compression
PERFECT!!! given my knocking/timing issues already
any thoughts or corrections to the above welcome lol
Just had a read of this honda thread ^^, which talks about moving the powerband up the rev range with cam gears, if i want to do the opposite then as my powerband seems most potent between 7k and the 8k limit i need to do the reverse.
It mentions tightenting the cam lobe seperation angle which in turn increases overlap, so i therefore need to widen the lobe seperation angle therefore decreasing overlap. I'm presuming to do this i need to retard my intake cam and advance my exhaust cam?
that sound about right?
obvioulsy this is best done on a dyno for the optimal results but the principle is correct yes?
other sideeffects according to the honda thread of widening the lobe seperation angle will be..
- decreased cylinder pressure
- decreased chance of engine knock
- decreased cranking compression and therefore 'effective' compression
PERFECT!!! given my knocking/timing issues already
any thoughts or corrections to the above welcome lol
Joe is right, retarding the base timing is just retarding the whole map. It's like fitting a AFPR and upping the pressure it's dumps more fuel everywhere on the map. Your losing 11* in every area of your map, I'm not surprised it doesn't open up until 7k.
I would of kept the base timing to 15*, then just pull timing back box by box until pinking is gone. 12.5:1 should be fine on 99ron in a VE. They have a much better combustion chanber than a DE. You sure it wasn't piston to valve contact?
I would of kept the base timing to 15*, then just pull timing back box by box until pinking is gone. 12.5:1 should be fine on 99ron in a VE. They have a much better combustion chanber than a DE. You sure it wasn't piston to valve contact?
if it was contact it wouldnt have stopped, he'd still be noticing it.
My head hurts now...
Some of the stuff on there goes against my original understandings...
My understanding was that advancing the intake cam (tightening the lobe separation angle) SHOULD increase low down power and make more peak torque.
Effectively by tightening the LSA you are making the intake valve open sooner (more ovelap) , and the intake valve close sooner. A result of the intake valve closing sooner is that on the compression stroke less air is bled (wasted) out of an open intake valve. The sooner the intake valve closes after BDC, the more compression you make. Compression makes torque.
This is what im sure the SR20DE lads were doing with the big cammed/big header c3/c6m setups. The big cams make the motor pretty flat in the midrange (low dynamic compression) so they advance the intake and retard the exhaust to give a stronger midrange. These were 10:1 or 11:1CR motors so the advance really helps them.
I agree that you should widen your lobe separation angle for the side effects they listed, but only because this will alow you to run more ignition advance, and thats why i think your motor feels a bit flat:
- decreased cylinder pressure
- decreased chance of engine knock
- decreased cranking compression and therefore 'effective' compression
Wider lobe separation will reduce overlap, improve idle and broaden/flatten the torque curve, making the power hang on longer. The later closing of the intake valve means more air is bled off, reducing your dynamic compression.
Like Joe said, i agree its the ignition timing causing the flatness. So you can either widen the LSA to try and run more ignition advance, or you need to look at running a higher octane fuel, perhaps a methanol mix.
I suppose the VE motor is more complex having two cam profiles, 12.5:1 is a high CR, you'll need lots of ignition retard on the low lobe, but then you can chuck loads of ignition advance back in once you get onto the mother lobes.
I'll leave it at that because im just rambling on now...
Edit: I feel there is lot more to it, especially the effects of overlap and scavenging, but i wont pretend that i understand it all which is why i'm gonna leave it there.
shaggy_master
brapp brapp!
Dale you are a fucking VIP
definitely not contact no.
as for the timing thing, i'm not sure it was base timing rhat was put at 4'. the timing was checked and was at roughly 15' then all other adjustments were during the road mapping on the laptop, which is surelythe map thats being adjusted not the base timing?
i gave the n1 specs to CP who said there's loads of room, and there is
lolDale, woahhh lol. you lost me big time. Now MY head hurts haha - thought i was onto something then but maybe not so much, although i agree i should increase lsa anyway for the knock benefits
just waiting on a reply from jez as to what exctly went on with the timing map/base timing malarky
agree with kurt too, goin on all the US builds with some v power 99ron and maybe octane booster it should be ok, don't get me wrong it's ok as it is, quick and smileson face, but it should be awesome all way through revs
we'll see, cheers for help sluts
shaggy_master
brapp brapp!
The comp's not too high slag 
The comp's not too high slag
yeh i've a feeling you're right.
thinking now i'm gonna use vpower, some of that aldon octane booster whichis supposedly awesome and independent tests show it to raise 98ron to 103 when a litre bottle (£9) is used per ttank. when used half a bottle per tank it still raises it a few octane points.
Dale, or anyone, shall i bother trying this lobe seperation angle thing like tomorrow? and what do you think will make much difference? i was gonna retard the intake 5' and advance the exhaust 5' too, but is that a bit much? just do 3 each and see?
Are you using adjustable cam gears? If so which ones are you using? I'm trying to decide which ones to get, the purple ones on gspec or bc ones on ebay.
Well i'd go down the line of sorting the N1 cam switch points, get your MSS switching the cams independantly of each other first.
Sort the oil burning out too...
....THEN get yourself another mapping and dyno session and get the igntion timing optimised, and then look at cam timing if you still arent seeing the results you expect. I think sorting the switch points out so that they engage independantly will make a good difference to the power delivery too. From what ive seen, a 600rpm gap seems like a good setup. Perhaps 5300/5900rpm with N1 Cams.
Im not going to encourage that you mess with your LSA and base ignition timing yourself, its needs doing by a tuner on a dyno with headphones to listen for pinking and make to the necessary adjustments to the fuel and timing maps. (.... and I dont want any responsibility if you fuck it up) :lol:
I think it just needs some more tuning time... as you said yourself, you ran out of time for a dyno session due to problems and you had to have it road mapped intsead.