I am dying to hear the outcome.

For reference Forte, I have a 3.4L Carrera with factory Motronic.

I too only get full boost (1-bar) in 1st gear at nearly 5500RPM, 4500 in 2nd, and <4000 for 3rd and 4th (T-4 flanged Turbonetic T60-1/0.81 A/R IIRC).

Since you have a G-50 as my Carrera has, a 3.4L motor EFI, T-4 flanged, and going to a Garrett, it is nearly apples to apples comparison between our cars.

Please report back as soon as you can! :)

BTW, I've hit as high as 447whp. 427whp dyno sheet on hand. Hopefully will get to dyno soon as my friend offered to pay. This time with really cold temps instead of ~70 degrees when the others were done. Maybe I'll break through the 450whp mark?

Tippy, and (others) who contributed to my orig post - I am getting the car back this week. I had the GT35R installed and .8bar spring put in. Check out the dyno on youtube (Frank Forte GT35R 930 turbo - YouTube). Putting out 460RWHP at .8Bar and full boost by 4000 RPM. Tuner says is spins the wheels in 1st and 2nd no problem. The motor was built to handle higher boost but I prob won't go higher than 1BAR and my tuner is very conservative (which I actually prefer)..lol

I'll report on my first test drive this week - I can't wait.

Did you go twin-scroll?

You said full boost at 4000 RPM. What gear?

If you did that in 1st with a G-50, we have a winner. If it is 4th, that is about where I am at now. And like you, I want mine to make boost in 1st at a decent RPM, not full boost at 5500 RPM where I have to shift in a split-second banging the rev-limiter every time.

Told you you'd be happy with the 35R ;)

There isn't enough load on the engine in 1st to create full boost earlier with a single turbo that's capable of flowing 650hp. If you want even quicker spool, go for a smaller GT3071R turbo (less top end power), or a pair of small twins on shorty headers.

Frank - that's a pretty healthy result from .8Bar!

Do you have a cat on the car? Sounds nice!

I'm like a lion staring down a zebra right now...............I wanna know if you went twin-scroll and what gear you make full boost @ 4000 RPM?!?! :D

I did not go twin-scroll....I pick up the car on Sat mor and will be sure to offer a detailed report and/or will road-test to answer any specific questions. Spoke with tuner today and asked "more" questions...he was clear that the car hit full boost in 1st gear by 3100 (not 4000 rpm) and broke the tires free easily throughout...in 2nd and 3rd full boost by 2900...Frankly, I don't believe it but he said the "car is just amazing" and responded better than they ever thought - said "it feels like the pedal is connected to the turbo".

I tried to talk him into (like it 's his car..lol) putting at 1.1 BAR spring in NOW - but he felt that a better option would be to put a variable digital boost controller in that steps up boost in each gear (.8 in 1st and 2nd; 1 in 3rd; 1.2 in 4th and so on). Thought it would put less stress on the drive train and get more control. I like this idea - for the next spring $$$$

Agree, an EBC is the best option for accurate boost regulation. Just don't get TOO TEMPTED :D

HOLY SHI'ITE! Full boost in a G-50 in 1st gear by 3100 RPM? That's amazing!!!!

That is 2400 RPM sooner than mine. Very impressive.

If you back up what the tuner claims, that'll prove how superior the newest Garrett's are and ball bearing technology.

Told you that was a good turbocharger for your engine. :-)

This is a built-in function on the Motec M600. I can't recall if the M48 can do this.

The APEXI AVC-R EBC allows you to set different boost levels for each gear :cool:

Just an option if your Motec ECU can't ;)

Just drove the car back from tuners (Dawe Motorsports).....AMAZING and freghtening power and torque throughout the RPM range. Full boost in 1st Gear between 3000-4000 RPM ..hard to look down as the rear end was ALL over the place, 2nd Grear saw .8BAR around 3000RPM and rear end began to sway, 3rd Gear a quick wiggle around 3000 and then a missle-like linear pull to redline.....awesome. On-ramps felt like a pinball when the plunger first launches the ball..lol

The tuner said this was the fastest single turbo-car they ever built and were surprised by the perf of the ball bearing (GT35). Guys - I am only at .8BAR and despite my initial protests for 1+BAR, I couldn't image needing anymore power (did I just say that?). Beyond my driving capabilities at this point.

As described - the turbo feels connected to your gas pedal. Linear but still the infamous single turbo kick-in-the-pants feel. Have to say Chris (TurboKraft) told me this from the start, but I was a skeptic. Engineer by schooling, I questioned the step-function improvement gains people described. Sorry Chris...and ..James (who finally talked me into it)....at least I didn't learn the hard way and go with the KKK!

PS. there were 2 people or 400lbs of smiles during my driving "exibition"

One more thing - I was advised to NOT get the anti-surge option with the GT35....in fact, mine came with it and I swapped it out to the conventional intake. Anti-surge could compromise a few hundred RPM of response and I didn't want any question. No surging at all with this motor, and I suspect most of these engines.

Sweet! Good to hear you're loving the new setup ;)

Seriously, go to 1bar and utilize the compressor efficiency of that bad boy! I ran mine at 1.25bar for years and it was just an animal! Killed everything on the road in outright acceleration... It was brutal :cool:

Come the spring, I will probably put in a variable boost controller and/or control with Motec. I would like to increase the boost a little bit in each gear and maintain reliability on the engine and drive train. I can't imagine many sports cars having the acceleration this has....it just keeps pulling hard til redline. Great recommendation!

Aw man, I'm so jealous! The boost response sounds unbelievable!

If it were a 930 box, the boost onset would be even sooner in 1st. Insane.....

Frank, the need for the anti-surge compressor cover depends on the engine specs.
A build yours -- more displacement & compression, head preparation, large tube headers -- usually does not need the anti-surge.
A more basic engine can more easily experience surge and need that version of the compressor cover.

With GT40 (a/r .89), GT2 cams and 3.4l, i've got full boost at 3000rpm in 3th gear.

Only 150/200rpm later than with my old GT35 and 964 cams :)

Took the car out again on Sunday.....WOW, it can't believe the acceleration. I am getting better at anticipating the wheel spin and learning to control the launch.

On a hard downshift from 4th to 3rd, on highway, I noticed what felt like a momentary "ignition-kill" (RPM/boost dropped as if shut off) and then back to normal and didn't do it again. Motec showed no flags (RPM limit and/or MAP limits well under limits). This happened once before and during tuning - Tuner put in hotter plugs, and checked the voltages and connections at the coil-packs. Some tweaks were done, but the "Ghost" reappeared yesterday. Seems like something minor or in the programming.

Anyone have any clues?

I had to run a Crane HI-6 ignition system on mine because the boost would cause ignition breakdown under load, however, that was at 1.25bar... Unlikely that's your problem at only 0.8bar :(

hmmm....it happened very very randomly (ie. noticed on a couple hard downshifts as described) and boost was not at full (.8 Bar) and was only momentarily - and then pulled hard to full boost and max RPM's. The motec has expander module with direct fire to 12 plugs...this should be sufficient?? What were the symptoms of "ignition breakdown"?

Engine hesitation as boost built up quickly to max... Once the hotter ignition was installed, never had a problem with hesitation. The charge air would essentially blow out the spark from the OEM ignition.

Doesn't sound like you have that issue though, with the DFI setup.

Hmm...what brand and type of spark plugs are you using? I'd go with simple copper type plugs and stay away from multi tipped spark plugs (i.e. two or four tang over an electrode). Also, make sure your plug gap is not excessive.

Frank,
Ignition breakup usually occurs under high load, high rpm - and unlikely in the scenario you're describing, boost pressure, ignition system you have, etc.

What it sounds like to me is an overly rich condition caused by too much throttle accel fuel. Are you setup to log wideband O2 on the street? Should be easy to confirm.

This happens to me on the factory Mototronic; if I stab the throttle sometimes after a high-RPM decel, the engine does not respond a lick!

Never understood what was going on.

Ok...so all 12 plugs are new single-trode with .023 Gap. Car was dyno tuned with wide-band O2 sensor and street tuned. We went through all the connections, voltages, etc....carefully and found no issues. Motec data logger shows no flags/errors. I am wondering if it could be an intermittent Expander or a ghost in the Motec? It's seemingly random so might be something loose that shows up on hard accel or decel??

Using the Motec M48 - which I understand is robust, but the logger software is hard to work with/check.

I would check acceleration enrichment settings in Motec ECU if the engine stumbles when pushing the throttle during overrun.

Frank,
If the problem is repeatable, it is likely a throttle fuel accel setting in your tuning file that needs to be adjusted. I've owned/had built half a dozen tuner cars over the years and there is always a fair amount of fine tuning that needs to be done off the dyno.

Dyno tuning is great for a very narrow band of cells that are hit during WOT and other's that you'd see during cruising. The transition cells (accounting for probably 75% of the map) can be roughly approximated from the dyno - but are typically dialed in further from logs from your normal driving. You can't physically hit all the load points the car will see on a chassis dyno.

Your tuner did the right (aka conservative) thing as it sounds like he left these transition cells on the rich side.
Best,
John

John, seems logical but why would the momentary hesitation and drop in Tach (to 0) while driving/accelerating in 3rd. In other words, on one ride - it did it when accelerating in 3rd gear. A brief (felt like ignition cut) hickup and then okay until redline. Couldn't replicate.

Think you could see it in the motec data if it was rich condition? I couldn't see it.

Frank,
I didn't see you mention the Tach drop to 0 in your initial post. That certainly does change things. I've only seen something like that as a voltage regulator was going bad... but afterwards the idle and tach would act erratic.

I don't see how hotter plugs could solve a problem like that... sounds like an electrical issue to me.

You'd definitely see a sub 10 afr on the datalog. Are you able to log ignition advance and voltage?

Just came back from test ride.... I was able to repeat the problem.....every time I would downshift from 4th to 3rd (i.e. taking off ramp) and immediately get back in the gas (start to build RPM/Boost) - there would be a significant hesitation, tach would drop , and then a huge backfire - and then the car would resume boost and RPM like normal.

When just accelerating hard up through the gears - no problems at all. Just when doing the highspeed downshift and then getting back on it. Strange?

Other than that - car runs amazing with no hesitations and is very responsive at all loads and RPM ranges.

Sounds like a very lean condition during a fast load transition?

Your tuner should be able to replicate on the dyno whilst monitoring the maps and AFRs etc?

Lean? I would have guessed rich due to the backfire

Did you log the drive?

John, I did and am looking over the data now..I plotted the RPM vs. Throttle Pos vs. MAP......I am looking for the pt at which the TP is WOT and the RPM is flat (i.e. where the blip occurs, followed by backfire). It was very noticable, like a Rev limit was hit and seemed to last at least a second - so I should be able to see something. I am not familiar enough with the software to know the flags...I wish some error codes came up??

I also sent to my tuner - and he didn't see anything either - but we must be missing something?

Frank - I'm not familiar with MoTeC's sotfware, but there should be the ability to overlay O2 with the plot of RPM/TPS/MAP. What's the air/fuel ratio as you see the throttle % increasing during that particular part of the map?

Do you notice the blip as you are rapidly opening the throttle, or is this a second after throttle is 100% and boost is ramped up?

John, I will post a screen shot tomorrow with an overlay of O2 as suggested.

It happens after I downshift and a second or two of WOT as the boost and RPM's are rapily climbing - and then it bucks, tach drops and backfires really loud. Then, if I lift off the gas (natural reaction as it's backfiring), and get back in it - it's fine to redline and full boost.

Think of a scenario where your racing someone, and need to drop a gear to hit the boost sweet spot. It does it everytime ONLY in this scenario.

The fact your tach drops to zero and the backfire makes me think you are having a momentary drop out of ignition.

What is causing the condition? That's to be determined.

Frank,
If you've already hit 100% TPS prior to the backfire, and you're not noticing this anywhere else with rapid throttle changes, it doesn't sound like throttle enrichment is the problem.

Hopefully your tuner will be able to zero in on the problem, if you can duplicate the situation for him in the car. I've been using aftermarket standalone ECU's for many years now and I've never experienced anything like you describe.

By the way, noticed Tippy's comment earlier about experiencing this with the factory ECU. Do you still have any of those stock components in the car?

JBurer, could the TPS going to 100% and switching from off-boost ignition parameters in the maps to the on-boost ignition parameters transitioning cause a hiccup?

Thinking out loud here.....