CAMS 2B/2F Prodsports Rule Changes - Turbos

[CrazyRacer]

It looks like CAMS has just released the 2018 rules for Prodsports and there are some interesting changes especially in 2B around turbos.

http://docs.cams.com.au/Manual/Race/RA16-Group-2B-2F-Eligible-Comb-2018.pdf

Exhaust manifold is now free and the turbo can be replaced as long as the compressor inlet housing diameter is no larger than 110% of the size of the inducer on the original compressor wheel.

Any thoughts on what some good (and preferably cheap) turbos might be on an SE or SP?

Obviously calling the car an SP and upgrading it from there is going to be better, but that does mean sourcing a VVT engine (or at least head) which makes it a bigger project for us SE owners.

Yes, maybe this should be in the forced induction section, but it is motor sport related.

[NitroDann]

Ive already got a few setups ready for the new rules.

As to what turbo is the go... i could post you one on an appropriate manifold.. for a fee.

Dann

[CrazyRacer]

i could post you one on an appropriate manifold.. for a fee.

Somehow I knew you were going to say that

Just wondering if I was to try and run it as an SE, I guess I'd be looking at something like a GT2554R and whether its going to offer enough benefit over the IHI to make it worth while.

Or run it with the IHI with a few mods for now and save my pocket money and run it as an SP with a VVT engine and a better turbo later.

[Nuddy]

No change for 2F?

[Nuddy]

Interesting - in 2F "camshaft(s) are free". "Where a system is deemed as free, all components solely associated with that
system are regarded as free" Thus VVT is your call,
But in 2B there is no mention of camshaft(s) so VVT must remain if it is there standard.
So for 2B my 2.5 is legal but my non-standard camshafts and disabled VVT are not.

[CrazyRacer]

I was more focusing on the 2B rules due to the new turbo freedoms.

This was my problem rule

4.2(a) The cylinder head/s must be those that were standard for that particular model. The cylinder head/s may be modified only by the removal of metal.

So (by my interpretation anyway) if I want to keep my BP4W head I'd need to enter the car as an SE and I'd be restricted to the size of the IHI compressor inducer (38.5mm) + 10% = 42.35mm. In the Garretts the GT2554R is about the only one I've found that looks like it would fit the bill. Haven't looked into other manufacturers, so there may be some better options out there.

By many online opinions the GT2554R is a pretty responsive turbo, but the Garrett site says its limited to around 270hp (maybe a little more on E85?)

Any experience with the GT2554R that you can share Dann?

If the car was entered as an SP, it has a bigger turbo to start with, so could go a little bigger again but I would need a VVT engine to stick to the rule above.

But exhaust manifolds are now free, so one of Dann's manifolds is now an option on either model in 2B.

Nuddy, I think camshafts are free for 2B under this rule

4.1(b) Save for the restrictions imposed in Articles 1.4, 4.2, 4.3 and 4.4, the remainder of the engine assembly and associated systems are free.

and there's no restrictions around camshafts in any of those 4 rules, so you could choose to disable the VVT or change camshafts if you wanted.

[NitroDann]

Any experience with the GT2554R that you can share Dann?

What would you like to know?

These new rules are going to allow MX5's to be genuinely competitive in these classes. I dont want to post numbers before these new setups have hit the dyno but they are extremely badass bits of kit.

Dann

[plohl]

You'll just need the BP6D head to run the car as an SP if I follow the ruling right. You don't actually need to run the vvt pulley, cams etc.
Not sure on how much power difference will be between using the se turbo or sp turbo as a base, but if you want to be competitive in 2b, you need to finish every race, aiming for outright power or most 'under the graph' might not necessarily help.
All the cars in 2b benefit from the rule changes, so I don't think the mx5 is going to get more competitive, the whole field might get a bit quicker. I see the best thing about the rule change is you could make a fast 2B mx5 easier, and probably cheaper, than previously.

[NitroDann]

I see the best thing about the rule change is you could make a fast 2B mx5 easier, and probably cheaper, than previously.

Me too.

[CrazyRacer]

You'll just need the BP6D head to run the car as an SP if I follow the ruling right. You don't actually need to run the vvt pulley, cams etc.

That's my reading of it too.

Not sure on how much power difference will be between using the se turbo or sp turbo as a base, but if you want to be competitive in 2b, you need to finish every race, aiming for outright power or most 'under the graph' might not necessarily help.

Given some of the quick cars in 2B, that I'd be building up a car from scratch, haven't raced in over 10 years and operate on a pretty tight budget I don't see being competitive as something I'd be realistically chasing. Main aim would be to have some fun, but faster is usually more fun!

I see the best thing about the rule change is you could make a fast 2B mx5 easier, and probably cheaper, than previously.

...and that's whats got me interested.

[CrazyRacer]

What would you like to know?

I've currently got an SE as a starting point that I'm looking at building up.

I guess I'm looking at whether swapping to the maximum sized turbo I can run as an SE is going to be sufficiently better than the standard IHI to justify the effort and expense. That's assuming either way I'd do some supporting mods like ECU, injectors, exhaust, inter-cooler etc.

Going the upgraded SP path probably isn't an option at the moment, but could be down the track.

But nothing is going to happen overnight, so happy to wait until you've got some dyno figures and discuss it then.