Advice for Boost Target for dyno tuning

[shri2222]

Hey, I am looking for some advice from someone with more experience them myself with turbo l28s 

How high on boost do you think I should go given the list of mods below on pump gas? I ask because I can't afford to blow this motor up and I have seen the results of many with a conventional f54/p90 setup but nothing much on a n42. 

I do have a goal of 350whp but safety at this point is more important. I was planing on running 16-18psi.. Am I to close to the threshold? 

 

Motor:

N42 block +0.030 over 0.75

ITM over sized dished pistons (the engine was bored little over spec, to compensate expansion)

Molly rings

Balanced crank

ARP rod bolts

ARP head bolts

Commetic 1.5 (.060) Head gasket

L28et oil pan

L28et oil pump

 

Head is N42 

Double valve springs

Molly retainers 

276 turbo cam

 

Compression ratio calculated to 8.13:1

 

N42 Intake manifold

KA24 t.b. 

 

stock log l28et turbo manifold

GT35 turbo 

external regulator with 8psi spring

 

600cc Fuel injectors

255 Walbero pump

z32 fuel filter

Custom fuel rail

 

LS1 coil on plug setup

Dist deleted.

 

FMIC

Big 1 quart oil cooler

3-Row aluminum rad

12" cooling fans X2

 

Exhaust is custom 3" turbo back

strait through 3" muffler

 

Computer is VEMs stand alone

running 4-bar MAP

V.R. cam and crank signal 

Edited October 6, 2013 by shri2222

[BLOZ UP]

Should be able to run that 350HP, at least, is my guess. Judging from my tuning of VG30Es.

 

It's all in timing as what I've learned. You can have knock from other conditions (too lean) but too aggressive timing is the main thing that will get you and not be so noticeable. That is, it's easy to see if you are running too lean, but timing values are very dependent. Is 20 degrees too much? Depends on RPM, compression, the gas you have, the temperature outside, boost level, etc.

 

So, start rich and conservative on timing and get the fuel table sorted out. Then work on timing (which will cause some changes to AFR, and some fuel table readjustment). For me, having the timing of the stock ECU was awesome, as well as the timing of people who make big power.

Edited October 4, 2013 by BLOZ UP

[SleeperZ]

Your hardware should be fine, a stock block and head can make those numbers with just a bit more boost.  Just make sure your fuel mixture, ignition timing, and intake/head temperatures are all good and stable.

[shri2222]

Thanks for the input . Knock is exactly what i'm concerned about. My stand alone has provision for a knock sensor. I'm going to look into see if I can add one before I go to the dyno.  VEMs is similar to Megasquirt, anyone know about any types of knock sensors I might be able to use?

[Lazeum]

I haven't tuned turbo engine from scratch but my guess would be to run the boost your turbo is designed for. Check out its map and see where is the best efficiency vs. rpm & boost.

With a GT35 and stock head (to be confirmed???), you would need to run some high boost to get 350whp but others have done it, just make sure, as it was adviced, to be conservative with AFR and timing especially during tuning.

[shri2222]

Lazeum, yes the head is a stock N42 just with double valve springs and turbo cam. I had intent to port the head, but that budget fell threw when I was told by the machine shop the motor needed to be bored out. I had matched the turbo to my rpm and cams when I decided to go that route, even spoke to the cam manufacture for their best advised cam for the GT35 to match with the revs I can run.  I have my AFR covered, I have dual widebands, one hard wired to the ecu, the other to a auxiliarygauge. 

[Sideways]

Fwiw my completely stock rebuilt to factory goodness l28et made a hair over 300whp on a dyno pack at 17-18 psi.  Youve  bit more compression obviously, so at that boost range youll be close to your "goal". 

[Tony D]

A GT35R at 17psi is flowing enough air for over 600HP

 

On a stock head, like Big Phils....you will surge it like a MF!

[shri2222]

I'll see what it does as we increase the boost up form the baseline. BigPhil did 388 -403 tq @25psi with a l28et with a 2mm h.g. very low 7.00:1 compression on a better flowing p90. his video with the bad waistgate and street tune  

 

If i run 14psi with my higher compression 8.13:1 hopefully I can get close to 350whp my tq should be pretty high I would assume 

Edited October 6, 2013 by shri2222

[z-ya]

Start consevative on timing. Like low 20s at 8psi. Like I always say, calibrate your timing before you do anything. I would think that you could reach your goal at 15psi. But it is not just going to happen. Plan on spending some time on the dyno. I am assuming you have a WB O2? If not, get one.

[shri2222]

Start consevative on timing. Like low 20s at 8psi. Like I always say, calibrate your timing before you do anything. I would think that you could reach your goal at 15psi. But it is not just going to happen. Plan on spending some time on the dyno. I am assuming you have a WB O2? If not, get one.

I will have 7hrs of dyno time in addition to break in time. I have dual widebands. The tuning shop is very reputable, they will start at the baseline 8psi to break in the motor once they build a map.  My concern is they tune and tune with good afr's up to 18ish psi all looking well and crack a ring from heat or have to much knock, since there is no knock sensor its hard to gauge. I want to add a knock sensor, but I don't know what others have used and place it 

[madkaw]

Never had read much goo as far as knock sensors, the best one is the two on your head(ears). Guys have made homemade versions using a hearing-aid device they sell on the late night infomercials. Basically using the mic from the hearing aid and putting it in the engine compartment to pick up early signs of detonation noise. Then you where a ear piece or headsets inside the car. Just google and you will find. It seems this device is more reliable then a knock sensor.

[Chris83zxt]

I ordered my MS3/MS3X with a knock module installed but I haven't decided whether or not I'm going to try to adapt the stock knock sensor to it or use an aftermarket "wideband" knock sensor.

 

I'm going for a one day megasquirt install tomorrow.  Unfortunately since Speedhut has taken over two weeks now to get my fuel pressure gauge w/ sending unit to me I probably won't actually be able to test fire it until Monday or Tuesday.

[Lazeum]

Detecting knock is not so easy. System has to filter white noise, noise from other sources (engine, roads, brakes, misc. items loose) & knock.

 

White noise could be reduce during detection by averaging it, other noises could be identified during regular operation (but you have to identify them) & knock can then be determined when something unusual happens.

It is not so easy and requires a lot of R&D to be reliable even if knock frequency is around the same for every engine.

NVH Signal processing is a science and requires some knowledge to be efficient. I've done this exercice at Bosch Brake systems Corp. on a 6 months intership while I was student to detect squeal on brakes. I was a 6 month project with a lot of coding with Matlab/Simulink, top of the shelf equipement and a PHD tutor who knew what he was doing.

 

On the other side, you could use your ears that can do this filtering quite easily as long as you've got the right tool to hear well & to filter surrounding noises.

I've made a DIY detcan that works quite well & cost $15.

I would be surprized if a tuner with a dyno wouldn't have his own professionnal detcan so you shouldn't have to make your own anyway.

Edited October 6, 2013 by Lazeum

[Gollum]

I don't like tuning with knock sensors. Tuning to the point that even a well calibrated sensor is detecting knock is a big NO-NO if you're trying to reach any kind of power limit. If you're only pushing a measly 100-140HP per liter then sure, mild knock shouldn't kill much, if anything, at all.

 

You've had some good advice, but I'll second some and maybe add some details of my own.

 

1. It's ESSENTIAL in tuning any engine that you know EXACTLY what's going on FIRST. Check timing accuracy. Get your injector data as close as possible. Make DAMN sure that your ECU knows where the engine is at in rotation and that it's getting clean crank signal. Try to fix noise issues externally FIRST before adding noise filtration in the software. Make sure your coolant and inlet temps are verified by a secondary source before you ASSume they're accurate and tune to them. Sensor calibration is a BIG DEAL.

 

2. Timing should be conservative at first. Make sure you're pulling timing under boost.

 

3. Tune fuel tables BEFORE timing, and consider that just because you might make more power at 13.5:1 at peak HP doesn't mean you might not want to add some extra fuel as a knock agent so you can be more aggressive with the timing once you get to spark tuning.

 

4. Before tuning your spark/timing do testing at low RPM and low loads to verify what timing your engine actually likes. Run the engine down to 12:1 AFR @1,500 RPM and find out where peak torque shows up when adjusting timing. Then lean it out to 14:1 and do the same. You can now calculate, if you take the time to do so, where your peak power will be under just about any condition. The challenge here is to know where to leave power on the table for safety, because it's not just at peak HP. There's actually a lot of space before peak TQ and after peak HP that you might want to stay a bit conservative if you don't mind leaving some power out there in the name of safety.

 

5. Make sure that your BASIC tables are well tuned and that everything seems to be going well BEFORE getting into all your other adjustment factors like cold start, knock detection, wall wetting, etc. You don't want these transient adjustments effecting your base tune, otherwise you're likely to cause bigger problems with your tune down the road.

 

6. And in all this remember to go easy and take things in SMALL increments. Don't get the engine running and drive straight to the dyno shop. I'd personally spend at LEAST 50 driving hours tuning part throttle around town settings keeping it out of boost long before trying to get adventurous tuning WOT. Obviously this means you'll be going back and forth between fuel tuning and then timing tuning, but that's the nature of the beast if you want it to be thorough. Of course the exception to this is if you rent a load controlling dyno for a whole day and can then tune cell by cell, but I wouldn't recommend this for a first time tuner.

 

 

I highly recommend "Engine Management: Advanced Tuning" by Greg Banish if you need some good reading material to get your head around the tuning process. It can be found on amazon here:

http://www.amazon.com/Engine-Management-Advanced-Greg-Banish/dp/1932494421

 

I've got several other books I own or have read and non of them are as clear cut and getting to the point without BS as this one. Lots of useful formulas and charts for quick reference.

 

Oh, and you should only need around 14-15 PSI to reach your goals with that turbo. In fact even a MILD street ported head @ 15 PSI should be capable of damn near close, if not over, 375whp. Big Phil's results were low, and many have different reasons they speculate, and he also had surge issues, which again, many people will argue about why and what is the best way to avoid that situation. All that said, dig through the advice TonyD has given on this forum on the topic. He only works on compressors for a living....

[Tony D]

Keep your fuel tank full on the dyno so the fuel doesn't heat up and start throwing off your fuel calibrations "chasing a lean condition"...

 

Anybody who adds fuel 5 gallons at a time because racing fuel is expensive deserves the days they spend chasing that lean condition that shows up after a few pulls and never seems to go ways (till you add another five gallons, it's resolved and on the next pul it's starts showing lean again...)

[kiwi303]

how hard is it to plump a oil cooler into the fuel line for the dyno day...

[Gollum]

how hard is it to plump a oil cooler into the fuel line for the dyno day...

 

Not hard at all. If you want to get really fancy take AC evaporator (cleaned inside and out of course) and hook it up to your fuel return line. Then for added awesomeness get a ice chest full of ice water and dump the evaporator into the ice chest.

 

How many of us have spare evaporators around? I know I've got several.... Just make sure to do it with the return for two reasons. 1. It's low pressure, versus high pressure, and 2. You don't want to cool the fuel down TOO much as it could skew your tune significantly as cooler fuel WILL cool the chambers more, meaning it will advance your optimal timing settings since a cooler charge takes longer to burn, leaving you overly aggressive once you remove the cooler from the lines.

[Gollum]

Also, if you're looking for a bit more permanent solution you can use a heat exchanger, but unless you add a secondary water source with pump, and instead use your engine coolant then there's a good chance you'll be HEATING your fuel. These guys can be fairly affordable though, and used in many fields where temperature control is crucial. A good example is in brewing where you want to extract your mash at a very controlled temp as it transfers to the fermentor as just a few degrees can dramatically change the flavor. By putting a valve on either your mash to fermentor or your coolant (usually tap water) then you can control the temp perfectly. Either way you use a valve on the outlet to prevent exchanger cavitation. 

 

I'm pretty sure when Honda was using exchangers to HEAT their fuel they were using a simlar setup, and most likely with a PID controller of some sort and a way to bypass it under WOT. Oh, and for those asking "why" they'd do that... Think economy...

 

 

Oh, and a link to a cheap exchanger that'll do the job just fine: http://www.dudadiesel.com/choose_item.php?id=HX1210&gclid=CNbY4pSemroCFSiCQgodSBoA8A

Edited October 16, 2013 by Gollum

[shri2222]

Wow allot of great information Gollum how beneficial is running a fuel cooler, especially on a street car that will see rare track days? This is a new concept to me I've never look into much.