Installed new cams now the car takes 10+ seconds to spool up.

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Bobbit

Active Member
Joined
Feb 25, 2014
Messages
25
Location
South Australia
Mods:
BC 284/280
Adjustable Cam Gears
Compression Ratio 9:1
ARP Headstuds
Evo Injectors (549cc)
18G TDO5
Sparkplugs: BPR7ES

So today i installed some cams i had ordered ages ago (BC 284/280) and other than the expected idle issues from first start (fixed) when i WOT the car will take an exaggerated amount of time to spool up and once it has "spooled" feels like pretty much nothing.
(Log shows about 10 seconds to get from 1.5k RPM to 5.3k RPM)

The current tune i made worked with the Stock intake cam and a HKS 264 Exhaust cam, the boost came on fast and hard but lacked a bit top end.

Pull starts at the 265 second mark.
View attachment log.2016.01.06-01(BC 284Cams).elg
 
Turbo and cams don't match very well. Your turbo likes to work early in the rev range. Your cams higher. Not really the best choice of camshaft.

Other causes may be the requirement to dial the cams in. Although installed as per factory specs, other factors including accuracy of machining and other if any material taken off the head or block. Ultimately relating to cam timing actual vs cam timing ecu.
 
Maybe if i reduce overlap by retarding the intake and advancing the exhaust it might work?
Either way though it shouldn't effect the spool or power that much right? It takes 10 seconds to go from 1500rpm to 5300rpm in second gear...

Cam spec sheet says install them at 0, head has never been shaved and block was only honed.
 
you will want to INCREASE the lobe separation ....what you have desribed above will close the lobes up.

So without being insulting....as we can all make mistakes

is it possible you have made a basic error in fitting the cam belt......check

is the ignition timing right

Are the afr right..lean/rich?

plugs are gapped correctly? gap not closed up?

waste gate stuck open?
 
Oh you are right, i had it the wrong way around lol.

I did it the lazy but annoying way of changing cams, where i zip tied the belt down to the cam gears so the belt wouldn't skip about and then done the swap, keeping everything lined up but i can check it again in the morning for peace of mind.

Set the base timing after doing the swap to 5 degrees.
Timing during the beginning of the pull was really high because the load wasn't enough due to the cams not pulling enough vac. the fuel was rich according to the narrowband voltage (not logging the wideband yet) but the AFR Est shows 12.9:1

Haven't checked the plugs yet couldn't find my sparkplug socket at the time.

Will take a look at the wastegate in the morning.
 
The problem is with aftermarket cams, is zero really zero?

Do you also know what your Max adjustments are? Do you have adjustable cam gears?
Piston to valve clearances ideally should be also measured to define your limits.
 
Had a similar issue with my old setup (everyone has heard this story before), on a 93t but with a bigger turbo (20g) and bigger cams (290) so could be considered comparable (sort of).

I had the exhaust cam retarded 4 degrees and the intake cam advanced 4 degrees via adjustable cam gears to try and get around the overlap, and it was still a very lazy setup. Don't be surprised if you get some improvement from what the guys have suggested but it's still not as responsive as you're use to.
 
Mivec advances intake cam 30° and intake movements are twice as effective as exhaust (according to kiggly). I think you might see a 1000 rpm difference in boost with mivec, so i can see vin statement being true.

i dont expect anyone to move their intake cam 30° tho. Beware of pistons!
 
He is talking about moving the cams. Im saying 4° thus way or that is sfa.
Im also saying its more effective to move the intake than the exhaust. Twice according to kiggly.
Im saying moving the intake 30° will affect spool by 1000rpm (according to kiggly)
He tested his at the full mivec range of 30°

Op may not have mivec, but twisting the intake a similar amount should give similar effect.
 
30 deg swing on either cam will see the valves meeting pistons.....
I wouldn't go past 5 either way on those cams ( measured at the cam )

In reality the cams are way too bug for that little turbo. As op mentioned the turbo is running out of puff as the cams are starting to work well.
I'd sell them and go back to a smaller cam if you are looking for better street manners.
 
What would i know. The evo 9 cam specs are in the workshop manual and state how far they twist them.
If you think im full of it, maybe do a bit more reading and less yapping.
Guys even grind the gears out to allow a extra few ° of twist.

Agreed, dont twist your intake cam that far unless you know what you are doing.
and the mitsi cams are not 280 either.
 
so....another question about how you did the cam timing. You say you used cable ties at the top to stop things moving. Did you use a long bolt to compress the tensioner then, release it after setting the cam timing?
 
Bobbit said:
336 seconds is a pull, i usually don't save my logs i just tune it after every drive and start a new one so its a bit old.
attachicon.gif
log.2016.01.01-01.elg
Click to expand...
Both of your logs have such bizarre timing, both drop to 1.1º BTDC around 2600-2800, yet are far too high early on. 34.2º @ 1800rpm which you have said you're aware of. That's a big contributing factor IMO

The first thing to do is what Brian has mentioned, check everything has been put in properly! Did you put the grenade pin in the tensioner and set the belt deflection properly? Make sure you check everything is still aligned after the belt is tensioned. It's all dead easy to line it all up.............However, as has been mentioned you need to dial cams in!!
No two engines share the same exact geometry, head and block being shaved or surfaced, different head gasket used.......these are all things that will change where the cams sit even if you put them back in the exact same spot.
While it won't make much difference on a std cam aftermarket ones, especially the BC cams will need dialling in.

You have Ignition timing not playing nice with cam timing......dial them in, sort out the tune. I'd be interested in seeing a log with boost as a captured value.
 
Benzo4gT said:
Both of your logs have such bizarre timing, both drop to 1.1º BTDC around 2600-2800, yet are far too high early on. 34.2º @ 1800rpm which you have said you're aware of. That's a big contributing factor IMO

The first thing to do is what Brian has mentioned, check everything has been put in properly! Did you put the grenade pin in the tensioner and set the belt deflection properly? Make sure you check everything is still aligned after the belt is tensioned. It's all dead easy to line it all up.............However, as has been mentioned you need to dial cams in!!
No two engines share the same exact geometry, head and block being shaved or surfaced, different head gasket used.......these are all things that will change where the cams sit even if you put them back in the exact same spot.
While it won't make much difference on a std cam aftermarket ones, especially the BC cams will need dialling in.

You have Ignition timing not playing nice with cam timing......dial them in, sort out the tune. I'd be interested in seeing a log with boost as a captured value.
Click to expand...
Boost is a captured value via the Omni3Bar sensor in the logs

So far looking at the logs compared to the timing/fuel maps the load is too low causing it to think its in the area for cruising hence the high timing.

I realise that i'll most likely have to check all the timing marks again and maybe reset the belt i think it may be off 1 tooth on the crank when the cam marks are lined up(can't quite remember).

Also here's a full pull in 2nd gear.. somehow managed to rev it out to the limiter.. sounded like it was retarding too much or missfiring in places though out the pull (similar sound to using launch control).
View attachment log.2016.01.07-01(2ndGearPull).elg
 
Crank at TDC, Cylinder 1 at TDC, Timing marks all lined up on the cams.
It's not that, so i'm happy that my first timing job went well.

Checked the plugs they were also good, looked at the stainless o2 housing and its gone from yellow which is about 320c now purple/blue meaning since the new cams its been hotter than 450c which goes back to the original conclusion of timings too advanced somehow..

Next week (hopefully) the parts i ordered will rock up so i can open up my exhaust to 2.5" because i'm thinking that the exhaust is one of the contributing factors (The previous owners exhaust goes from a 2" to a 2.5" to a 3".. its retarded) currently the o2 housing's flange is 2.5" but then the flange it hits is around a 2" i think.
 

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