MAP sensor only RB26 single turbo engines

[Chris Wilson]

I am now close to assembling my RB26 lump. Spec is as follows:

New N1 block, Tomei cooling channel forged pistons @ 86.5mm bore. Tomei forged rods, Farndon billet crank at stock stroke (same as HKS steel crank), Tomei high capacity oil pump, Tomei 280 duration cams with 10.8 mm lift, stock valve sizes, in new RB26 head casting, mildly ported and matched to manifolds. Intake side is stock plenum with 50 mm (bored out stock) throttle bodies. I will be running a single TO4 family turbo, and aiming for 600 BHP max. I will be running Motec M600 or M800 ecu. I want to ideally ditch an AFM and run MAP sensor system. has anyone real world experience of a well mapped single turbo engine of broadly similar spec on a MAP sensor system? How was drivability? Throttle response? Do you regret not sticking witha MAF sensored system?

Usage for the engine is track days in a stripped out R33 GTS-t bodyshell, with a possiblity of dropping in an R33 GTR rolling chassis at some future point for some fun on the roads.

Thanks.

[blk180]

N1 block has 87 mm bore so how are you using 86.5mm pistons

[PurpleR32]

I run a single and a Motec M800 on my 32.

The idle, drivability, Throttle response etc will only ever be as good as your Tuner and support systems. If you do go a M600 or M800, spend the extra money on someone who knows how to tune them. Even If that means flying someone over.

I am really happy with my result. However nige & karlos spent a long time getting it perfect. Personally i hate those pesky AFM's

:

[KamikazeR33]

i was told map sensor and multiple throttle bodies dont go well together

maybe this is different with a motec tho? SK would b able to answer this

[RPMGTR]

Get the M800/600 set up by a decent tuner using tps/map on fuel and map for ign and drivability should be like stock or better.

[Chris Wilson]

N1 block has 87 mm bore so how are you using 86.5mm pistons

Well, it's a brand new, in the Nissan box, N1 block, with N1 part number and it's a 96 mm bore. So not sure how to respond to that... I chose 96.5 to allow at least one more bore out of it for wear purposes, or a minor whoopsie.

[Sydneykid]

I should state up front we have 2 X GTR's running Motecs, one M600 and one M8. And I have used Motec's of all types on race cars for many years.

Personally i hate those pesky AFM's

Why?

It can't be power, I have seen an RB27 with 2 X Q45 AFM's make 1100 bhp.

It can't be speed, I have seen a 170 mph TS on a GTR with AFM's

It can't be time I have seen an 8 second pass..........

It can't be tuning, there is simply no better way to match fuel to airflow than by measuring the airlfow. Everything else is a compromise.

The idle, drivability, Throttle response etc will only ever be as good as your Tuner and support systems. If you do go a M600 or M800, spend the extra money on someone who knows how to tune them. .......nige & karlos spent a long time getting it perfect.

And that's the problem, I can get a car to run ALMOST as "nice" on the Motec's as I can on the Power FC, but it takes me many many hours (remember I have never claimed to be a good tuner) to tune the stuff that the Power FC comes pre programmed with. Motecs have nothing, you have to start from scratch.

An example, I can plug a Power FC into a suitable RB, drive it to the dyno and tune it for 425 rwkw in under 2 hours. All up cost (PFC & tuning) less than $1,600. It would take me 3 days to do the same with a Motec. I have not seen any evidence of achieving more than a handfull extra power with the Motec, but one thing is for sure I would have to get the car back a couple of times to fine tune the hot run, cold start, aircon compensation, idle quality and cold run that the Power FC has standard. All up cost (Motec M600, sensors & tuning) more than $5,000, depending on the enabled options.

The question for me is "can I spend the extra $3.5K" on something that will give me more bang for my buck?

PS; Chris, if you want to know more about setting up the Motec, please just ask.