high lift cams and vvt removal

[dave_sr20]

sorry if this has been posted a thousand times over but i couldn't find the info i was after so basically i have rebuilt my engine with acl bearings, arp bolts throughout, metal head gasket, valve stem seals and bc stronger valve springs as a basic overveiw and all is well with it but the vvt has started making abit of noise now and have been told that stronger valve springs do shorten the life of the vvt sprocket so i have looked up on removing the vvt with vernier pullies and high lift cams i have been quoted on hks 264 inlet and exaust cams and hks vernier pullies and is only £80 different to just getting a new vvt sprocket but was wondering if anyone else has gone down this route? have been told that i will lose bit of mid range but will gain bit more high end power and get the lumpy idle you get with high lift cams but im alright with that. would also like to know if running this setup with my current mods 2871r, stage 1a hdev chip running 1bar and standard afm and injectors would it run lean on throttle with the extra duration and air flow or will the afm sort things out, bearing in mind i will be sorting out set of 555s, z32 and a hdev remap soon aswell!
thanks in advance!

[hooky]

I'm using 286cams with no VVt and its great fun with a motorbike-type power band But im using a fully mappable ECU to tweak the idle maps for MOT's etc.

I you are still using the Hdev chip, then it needs to match the specifications for that chip, any mods that stray from this will require a custom map.

To be honest, a mappable ECU is the most future-proof option

[dave_sr20]

Ideal! Sounds like what I want really... What ecu are you running and where's best to get one? Was going to take the car up to Horsham when it's ready and get a custom map for that setup.. So if I fit it all now will it be an issue with running it with its current map?


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[Galant_X]

Why even bother with high lift cams and BS springs on a 2871 turbo?
Refit OEM springs and VVT, and you will get a mutch better running engine.

Running the 2871 on the stage 1 chips is no problem, as long as you keep the boost sufficiently low.
You will run out of fuel even at 0,5 bar with the 2871 on the stage 1 chip. removing the wastgate arm from the flapper is the safest bet.

[dave_sr20]

I done the spring as I had it apart and I will be chasing more power in the near future so wana lower the chance of valve float so deffenatly not refitting the old springs... And if I remove the actuator arm it will bearly make .5 bar if atall.. may aswell run no turbo with that setup? Thanks for your opinion though!


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[Chriscooke]

Poncams work well with the 2871r and I believe you can keep the oem springs etc. If you are running a 3a chip and 555cc injectors don't bother though as you'll need 740cc injectors and a custom map to make it worth while IMO.

[Actual_Ben_Taylor]

I'm using 286cams with no VVt and its great fun with a motorbike-type power band But im using a fully mappable ECU to tweak the idle maps for MOT's etc.

I you are still using the Hdev chip, then it needs to match the specifications for that chip, any mods that stray from this will require a custom map.

To be honest, a mappable ECU is the most future-proof option

286 cams? Is that a typo or have you got some crazy drag spec motor??

[dave_sr20]

Poncams work well with the 2871r and I believe you can keep the oem springs etc. If you are running a 3a chip and 555cc injectors don't bother though as you'll need 740cc injectors and a custom map to make it worth while IMO.

Iv looked into Pom cams and there pretty exspensive units compared to hks so I reckon I'll go with hks gear... So if I get 740s and z32 and run them with the cams on he map I have will it run well enough until I get the correct map sorted for it? I can't see why not as the air flow meter won't be maxing out so should still read the correct air flow? Or am I wishful thinking?

[Actual_Ben_Taylor]

Iv looked into Pom cams and there pretty exspensive units compared to hks so I reckon I'll go with hks gear... So if I get 740s and z32 and run them with the cams on he map I have will it run well enough until I get the correct map sorted for it? I can't see why not as the air flow meter won't be maxing out so should still read the correct air flow? Or am I wishful thinking?

When you factor in the cost of 8 new rocker arms (which you really should fit with the new cams), replacing the VVT pulley will probably work out cheaper.

Personally, after trying many different cam setups, I'd stick with the VVT (with aftermarket cams) for anything under 450hp.

[dave_sr20]

When you factor in the cost of 8 new rocker arms (which you really should fit with the new cams), replacing the VVT pulley will probably work out cheaper.

Personally, after trying many different cam setups, I'd stick with the VVT (with aftermarket cams) for anything under 450hp.

Are the rocker arms prone to snapping? Iv never heard of it only ever heard of them jumping off? I could be wrong ofcourse!

[hooky]

286 cams? Is that a typo or have you got some crazy drag spec motor??

A very slight typo, They're actually 285's, originally for a DE fitment. I used these with a GT3582 for a couple of seasons with some N2O to spool it up, but i got tired of breaking things, so am now left with these cams in a solid lifter head and currently 8500rpm with a 9.5:1 compression and a low boost (0.9bar) blower

[Actual_Ben_Taylor]

Are the rocker arms prone to snapping? Iv never heard of it only ever heard of them jumping off? I could be wrong ofcourse!

Not so much, but you wouldn't really want to use new cams with worn rockers.

[Actual_Ben_Taylor]

A very slight typo, They're actually 285's, originally for a DE fitment. I used these with a GT3582 for a couple of seasons with some N2O to spool it up, but i got tired of breaking things, so am now left with these cams in a solid lifter head and currently 8500rpm with a 9.5:1 compression and a low boost (0.9bar) blower

Ah I have 268/272 stagger, so thought you might be running the same

[mikeyrs]

Iv looked into Pom cams and there pretty exspensive units compared to hks so I reckon I'll go with hks gear... So if I get 740s and z32 and run them with the cams on he map I have will it run well enough until I get the correct map sorted for it? I can't see why not as the air flow meter won't be maxing out so should still read the correct air flow? Or am I wishful thinking?

short answer, no. if it runs at all it will run badly.

[dave_sr20]

short answer, no. if it runs at all it will run badly.

Okay so what about if I get z32 and injectors and do the lot in one then get it mapped suppose this is my only option?

[dave_sr20]

Ah I have 268/272 stagger, so thought you might be running the same

So say about a staggered setup I did get asked when I got a quote in the bits a option on the exhaust cam to run a 272 but what Benifit will this give me?

[autosri]

Do you even have a wideband to see if your already killing the engine with the 2871r and 370cc injectors before you even whack in the cams

I doubt the engine will even start with a map for 370cc injectors but 740cc injectors fitted and if it did you would have fuel virtually pouring out the exhaust and just sticking any old air flow meter in and hoping it won't lean out too much is just crazy


I think you really need to talk to a proper tuner about this mate

If it was me I'd spend a weekend fitting everything to the car so injectors cams airflow meter boost controller ect then have it trailered to your tuner

[dave_sr20]

Well this is why I'm asking what others have done... From what I know from an air flow sensor does I'd of said it would sort it self out aslong as its within its perameters but like you say I don't have an agreement gauge so unsure if it's running lean as it is... I think what you say is right I will gather the parts and do it all in one and then get it up to the tuners so that I don't have any issues! Thanks for your advice!


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[autosri]

These are not actual figures but say the stock afm reads 10cubic meters of air and gives out 1v to the ecu it injects 100cc of fuel now say the z32 maf reads 10 cubic meters of air and gives out 0.5v the ecu will only inject half the fuel so will run lean
The stock afm and z32 meter run the same 0-5v output but the z32 will flow more air before it hits5v

Now the injectors the stock are 370cc so say when you start the car up from cold it runs quite rich say 12:1 AFR so 12 parts air to 1 part fuel if you fit the 740cc ones that's twice the size so when you start it up and the ecu is running on the warm up map you could de spraying twice as much fuel in which would put you at 6:1 AFR as the injectors would still be opening for the same time which could be washing all the oil of the bores

I'm still getting my head round this part so could be wrong but just cus your running 1 bar on the t2871 it's gunna be flowing more air that a t28 at 1bar so you could currently be doing irreversible damage to the engine

[dave_sr20]

That make sense to me thanks for explaining that to me... Before I took the engine out to rebuild I ran the standard t28 at 1.3 bar on the same map and it ran as well as it does now and I found no issues with the engine when I stripped it was all in good order only rebuilt it as I had the opportunitybro do so but I will bear it in mind and turn the boost down.. What is a safe level to run the boost at for now then?


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