Turbo VTEC questions

As a few of you may know, I am building a Individually Constructed Vehicle(a Garaiya) using a Nissan SR20VET(NEO VVL + Turbo) motor and Nissan FWD gearbox, mounted into the rear like an MR2.

This is the specs for the stock engine cams:
http://image-cache.boostcruising.com...1809921956.jpg

Regarding all the boosted VTEC engines on this site, do you switch the cams as per normal rpm switch or switch the cams once the inlet manifold sees positive boost?

Do you use the low lobe to spool the turbo up faster? then the hi lobe for higher air flow?

What sort of cam specs is everyone else using?

Info from K20A+T owners would be appreciated.

you do two dyno pulls, one with only the low cam engaged, and one with only the high cam engaged. The two dynos are overlayed, and the vtec engagement is set where they overlap(or slightly lower with a bit of tweak to timing to smooth it out, but basically at the overlap).

This method will give you the optimal power from each cam as you're really narrowing down where one becomes less efficient than the other.

Thing is, the new turbo won't spool on the hi-lobe alone. It needs the low rpm lobe to generate enough exhaust flow to spool the turbo up :(

Looks like I have some experimentation to carry out. I need to pass a 'smog test' with this engine, so I was thinking that the low lobe for manifold vacuum up to 0psi and then hi lobe for boost would be a good idea.

if you need to pass epa just make sure you have a proper exhaust

Quote:

---

Originally Posted by iamhappy46

Thing is, the new turbo won't spool on the hi-lobe alone. It needs the low rpm lobe to generate enough exhaust flow to spool the turbo up :(

Looks like I have some experimentation to carry out. I need to pass a 'smog test' with this engine, so I was thinking that the low lobe for manifold vacuum up to 0psi and then hi lobe for boost would be a good idea.

---

0psig in the manifold will happen as soon as you go full throttle. You obviously cannot do a full power run with just the low, then just the high then see where they cross over. It is a great idea in theory, where cars magically tune themselves perfectly, but it's just not viable to do if you care about your time at all. Just have a reasonable guess, and if power is dropping off just after the cross-over, then up it a little; similiarly in reverse.

you can't do one completely with just the low and then the high, but say your expected cross over is somewhere between 3500 and 5500, you could do a run switching cams at 3000 and another run switching cams at 6000

It needs an exhaust emissions check(NOx, CO2, CO, etc) for the ICV to pass engineering.

The car has an electronic throttle body, so I can control the inlet manifold pressure to regulate 0psi(as much air as the engine can use) then once I am ready to increase boost, the ECU can open the throttle body fully and act as a 'boost controller' by limiting airflow if/when required.

Yes, I am making it more complex than it has to be but hopefully, the results will be worth it. Basically, the SR20VET was the last SR20 derived motor that Nissan built and is the only turbo charged engine that passed the much stricter Japanese exhaust emission laws. I am trying to emulate their tuning philosophy in an 'attempt' to get my engine passed.

hi iamhappy46.
Are you planning on building it from scratched? i.e. chassis, donor engine, donor sussy etc etc? Have you looked into ADR emmissions regulations applied on ICV's? I dont think its possible to get it engineered and road registered if your planning on boosting a stock engine. Its already hard enough as it is with getting a stock engine into an ICV and getting it registered let alone a boosted one. For example a stock 4age 20V running the standard ecu cannot be used on ICV even tho they have been proven to pass emmissions under the ADR 79/01 code. There is a new ADR out now as well. Let us know how its goes mate.

Quote:

---

Originally Posted by Boost

hi iamhappy46.
Are you planning on building it from scratched? i.e. chassis, donor engine, donor sussy etc etc? Have you looked into ADR emmissions regulations applied on ICV's? I dont think its possible to get it engineered and road registered if your planning on boosting a stock engine. Its already hard enough as it is with getting a stock engine into an ICV and getting it registered let alone a boosted one. For example a stock 4age 20V running the standard ecu cannot be used on ICV even tho they have been proven to pass emmissions under the ADR 79/01 code. There is a new ADR out now as well. Let us know how its goes mate.

---

Any links to where I can find emissions regulatins for ICV's?

That's pretty damn stupid the with the 4age. If the rta genuinly cared about emissions they'd make people pay extra for ****in imitation 4x4's which chew through 4 times the fuel that a 4ag will.

Quote:

---

Originally Posted by Boost

hi iamhappy46.
I dont think its possible to get it engineered and road registered if your planning on boosting a stock engine.

---

the SR20VET is a turbo engine from the factory, so he is planning on using a stock engine
came in the XTrail GT.

Garaiya?
as in the GT300 Garaiya?

I have a wreck of a Garaiya on its way from Japan(arrives this week) I have already started building a chassis and will fit the Garaiya body onto my chassis with a S15 Silvia headlights, Mazda Series 8 RX7 rear lights and some custome fibreglass.

The GT300 Garaiya is a race version of the street driven version in the pics below...

Chassis uses R32 Skyline adjustable wishbones, coil overs, brakes(R34), adj. castor rods, etc so I can fine tune the suspension. Should weigh in just over 800Kg and my engineer is happy to pass a 2L turbo as a street driven car with that weight/brake setup.

I am using my spare factory SR20VET engine but the engine is far from stock. It should hopefully pass all relevant testing though but time will tell. It will be on the dyno this week

http://f5.putfile.com/5/14807434429.jpg
http://f5.putfile.com/5/14807451626.jpg
http://f5.putfile.com/5/14807523266.jpg
http://f5.putfile.com/5/12803040778.jpg
http://forum.pulsar.org.au/attachmen...1&d=1152147891
Damn that looks sexy
http://forum.pulsar.org.au/attachmen...1&d=1152147891
Where did I put those Kleenex?