Magnuson 1900 Project- over-drive Cog, Porting, & Cutting out restrictions....

[hflores3]

I did some searching yesterday- came up empty


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[L3AND3R]

After having stumbled upon this thread I decided to dig in and ported my 1900 Maggie's lower manifold and while at it also opened up the TB. Here are my experiences and some resultant questions to those in the know:

My setup:
2009 6L Lumina UTE
Factory Auto trans
Factory stall
Standard cam
Standard engine
Maggie factory tune
2.9 front pulley
Standard 1:1 rear pulley set
10Psi @ 6000rpm
Pacemaker 1 7/8 long tube extractors
Dual 3" exhaust cat delete
CAI Roto-Fab
AEM Meth Spray pre TB
Pump gas 95RON
39lbs injectors designed for boosted applications

BEFORE porting had massive torque from 2000rpm. By 5500rpm engine ran out of breath. Best progress was made shifting at 5500rpm. WOT AFR 12.0 (no meth) average throughout. Engine pulled strong and smooth at WOT everywhere even without meth.

AFTER porting power came on very strong at 3800rpm. Pulls very hard onto 6000rpm limiter now. WOT AFR (no meth) 12.5 average. Now Surging at WOT up to 3500rpm. Cannot use WOT below 3500 rpm. WOT Timing 3*deg below 3000rpm, 7*deg @ 3500rpm, 11*deg @ 4000rpm, 12*deg @ 4500rpm, 13*deg @ 5000rpm+. Timing pulls back to 8/9*deg without meth.

Part throttle response very sharp & smooth from low rpm to high rpm.

Is it possible to get the WOT response at low to medium rpm restored with tuning the map? I've learnt to only go WOT from 3500rpm, but this is not ideal since I'm not the only driver of the vehicle.

Any input will be greatly appreciated.

[Doug Hilliard]

Hmmm. It does sound like a tune issue although I'm amazed you can get by with 39lb injectors at 10psi and no meth. My car is the subject of the original thread but I have since changed to the LSA blower. Rick (who started the thread, did the build and tune) is a great one to get some input from. He is so busy I'm not sure how often he checks the forum these days. You might forward the content of your post to him at LS-4-Speed@nc.rr.com and see if you get a response. I'm guessing you are down under as you use the term "extractors" for what we in the US call "headers." Feel free to e-mail me as well at drhillia@bellsouth.net if you want to correspond off the forum as it might be easier. Rick can remote tune for you but you have to have HPTuners to do it.

[L3AND3R]

Thank-you Doug for your reply. I must have read this thread about your car and watched the YouTube clips of your passes more times than I can remember. I realized Rick became a very busy and famous tuner since the days of the start of this experience. You are also quite correct, I'm way down under on the dark tip of Africa where accessible knowledge about the more intricate aspects of L98/76 tuning is sadly lacking.

I've ordered my own copy of HPTuners for the very reason that I'd prefer getting it right systematically rather than leaving it to a dyno tuner with all the difficulties accossiated with heat soak, trail & error and so forth. Maybe trying Rick is not a bad idea even if just some pointers in the right direction will come of it.

I have subsequently installed a meth kit spraying pre throttle body and this seem to have made a bigger difference overall than even the porting of the lower blower manifold did. Perhaps the meth is bringing the whole thing together. I must admit having completely underestimated the possible benefits of meth when I originally started this porting expedition.

Without meth I won't even think about WOT stabs anymore since the ECU just keeps pulling timing and the car then just feels lethargic and generally unhappy. It's fine under normal driving though where normal driving implies closed loop operation. My problems with drivability seems to start at the onset of the transition from closed loop to open loop in the region below 3500rpm.

I have a ScanGuage monitor mounted on my dash which is extremely informative in real time. I can monitor several parameters on the fly which is why I more or less know where the issues are.

Look the car is blindingly quick from 4000rpm onwards spraying full undiluted meth. Third gear roll-ons from 140km/h sees GSX-R1000 riders not able to come by. Same with a GSX-R1300 last weekend. I manage to keep them behind me right up to 280km/h when I let off. That's pretty fast enough for me.

Like I said in my previous post, I'm now chasing after regaining that little bit of refinement the excesize sacrificed.

[Doug Hilliard]

I'm always happy to offer anything I can but I only know what I've learned from Rick and the forums. Glad you've enjoyed the videos too! What do you have for monitoring AFR? It really sounds to me like you are out of fuel. Even when I was running 10psi, I had 60 lb injectors and a BAP boosting the fuel pump to 16V under boost. It sounds like you are running out of fuel and getting into knock and then the ECU pulls timing. With methanol, you are basically adding fuel and knock retard which gives you two improvements. On the other hand, it doesn't make sense that the car ran fine at higher RPM's even without methanol so that doesn't really make sense either. At any rate, I'm sure getting Rick involved will help sort it out.

[L3AND3R]

The car only really ran fine without meth prior to the porting of the lower manifold and TB. And even then it didn't ran so great without an octane booster. I always ran NF Race 6 RON on top of the 95 pump gas we have down here. My problems seem to have started with the porting. The dynamics changed there which is making me in hindsight think you may be on the money with the running out of fuel idea.

The only two times I had the AFR checked was on a before and after porting dyno run. Before it measured 12 through the midrange and 11.5 at the top. After porting on the same dyno it measured 12.5 through the midrange and 12 at the top. This was measuring with the probe stuck up one of the tail pipes.

To clarify the situation I've just bought an AEM Wideband AFR and my exhaust builder fitted the pickup midway in the x-section of the exhaust where two banks come together just after the headers. I'll have it all neatly wired up by the weekend and report back on my Findings.

[Doug Hilliard]

Sounds like a plan! Nice pic!

[08MGMGT]

This is one exceptionally put together post. Kind of new to the G8's, only owning mine a bit less than a year now. But a huge thanks to all in this post.

[hflores3]

Man you guys see the Lingenfelter CTS-V heat exchanger "system?" Very impressive! I really think that bad boy would fit outer G8s. Dual row, two 11 in Spal puller fans, 2-speed fans, thermostatically controlled - looks like it will bolt to the crash bar. Downside - big bucks.


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[Darkmanx]

How hard was it to separate the blower from the manifold