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Montego Blue Rotary: Gleaming in Reverse under Sunlit Skies !!
Instagram DMs are flooding in, with people speculating that the Montego Blue rotary is equipped with a Bridgeport after seeing it in action for 100-200kph runs. Let's set the record straight: this beast boasts a street-ported motor.
While performing a full systems check before increasing the boost to 25psi this weekend, I observed a recurring loss of coolant after each run. This raised concerns, and I'm seeking to understand the potential reasons behind this coolant loss.
The obvious one was did I kill the motor? or are the 250+ 100-200kph draggy runs catching up with me? Perhaps...so lets investigate further!
Took the front bumper off to have a good scan of the entire cooling system and make it easier to check for leaks.
Scooted beneath the car, and the mystery was swiftly solved. The water pump is showing its true colors, leaking from its regular spot and trickling out of the tiny orifice at the base. Looks like it's waving goodbye!
Luck was on my side this time as I combed through the data. Caught a break by spotting this early – a mere 50-60ml slipping away after each boosted run. The attention to detail has its rewards, as this could have been a catastrophic failure at 25 psi. Remember, every detail counts when you're in the realm of these machines, folks!
Summing up and aiming to capture these lessons for our shared knowledge...
I completed 10+ draggy runs at 15psi, establishing a baseline with the new excessive manifold and perfecting the tune. A pre-run ritual I always complete before starting the fd is checking two vital factors—oil level and coolant level.
In the span of 250+ runs I've logged, minimal oil or coolant loss raised no alarms. However, in this specific series, a disconcerting 50-60ml loss per run was noted.
Acting on it, I kept an eagle eye for white smoke during idle, cruise, and acceleration in the subsequent start-ups. Luckily, no smoke materialized, eliminating water seal concerns. Nevertheless, a coolant leak remained to be tackled.
Bumper off, an inspection beneath revealed the smoking gun: the water pump was the troublemaker, luckily no detective work required.
Always be vigilant around these machines, Gentlemen!
New oem water pump and relevant gaskets ordered via Amayama which should be here in a few weeks.
It shouldn't really matter, if you tune it just for the water. If you want methanol, convert your fuel system to methanol, if you want auxiliary injection, go for water, but use washer fluid so it doesn't freeze.
Adding methanol is adding fuel, and you have to account for that. It also has an octane rating.
The octane rating on water is infinite and not well understood imo. I recently posted a video on this over in the AI section. You might consider finding and watching it.
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as we increase the airflow into our motors both the IAT and combustion temps and pressure present a challenge to engine health, especially if base fuel is gasoline.
AI is a significant part of the solution. injectant can be water or methanol or any combo. water does little to lower IATs but works very well in the combustion chamber. methanol can greatly lower IAT. my recent logs show a temp out of the IC of 175 F and a temp after the methanol of 75 F....
water or 50/50 water/meth are significantly easier to manage as neither are combustible. plastic lines are fine and you can purchase a relatively inexpensive system.
if you choose to run a mix of over 50% methanol w water the game changes. you are dealing with a fuel that combusts. no plastic push-on lines. this would apply to your contemplated 80/20 mix.
i have run AI since 2003. my injectant is 100% methanol. i run an Alkycontrol system. same controller since 2003, probably a couple of pumps.
as you up the boost a bit you will probably be around 600 rwhp... this requires 4800 CC/Min net into the motor (gasoline). let's assume you are injecting 1200 CC of methanol, that'd be 17% based on volume. meth is 46% of gas as to BTUs. so it would contribute 8% of your fuel needs. if you tune to 10.3 and lost your meth your afr would go to 11.1. probably not catastrophic. i have never had a failure of my AI.
water or water/meth 50/50 is the solution for most... the key for you is that the 80/20 M/W is combustible and that changes the equation a bunch. . .
as we increase the airflow into our motors both the IAT and combustion temps and pressure present a challenge to engine health, especially if base fuel is gasoline.
AI is a significant part of the solution. injectant can be water or methanol or any combo. water does little to lower IATs but works very well in the combustion chamber. methanol can greatly lower IAT. my recent logs show a temp out of the IC of 175 F and a temp after the methanol of 75 F....
water or 50/50 water/meth are significantly easier to manage as neither are combustible. plastic lines are fine and you can purchase a relatively inexpensive system.
if you choose to run a mix of over 50% methanol w water the game changes. you are dealing with a fuel that combusts. no plastic push-on lines. this would apply to your contemplated 80/20 mix.
i have run AI since 2003. my injectant is 100% methanol. i run an Alkycontrol system. same controller since 2003, probably a couple of pumps.
as you up the boost a bit you will probably be around 600 rwhp... this requires 4800 CC/Min net into the motor (gasoline). let's assume you are injecting 1200 CC of methanol, that'd be 17% based on volume. meth is 46% of gas as to BTUs. so it would contribute 8% of your fuel needs. if you tune to 10.3 and lost your meth your afr would go to 11.1. probably not catastrophic. i have never had a failure of my AI.
water or water/meth 50/50 is the solution for most... the key for you is that the 80/20 M/W is combustible and that changes the equation a bunch. . .
Based on what you've mentioned my AI system is not setup for 80/20. The lines are the one's supplied by the AEM Kit so likely wont take 80% meth.
I'll leave it at 50/50 mix and turn it up to 24 psi and see how it goes.
Adding methanol is adding fuel, and you have to account for that. It also has an octane rating.
The octane rating on water is infinite and not well understood imo. I recently posted a video on this over in the AI section. You might consider finding and watching it.
.
I really enjoyed the video. Anyone who is running AI should at least take a look at it. It made me more comfortable with my decision just to use washer mix. To be honest, before seeing that, my main logic was I got sick of buying methanol and mixing my own. I think at one point I had 6 5gal cans around. Much easier to stop at a gas station and fill up on washer fluid whenever needed. And my general though is it's safer to not have a tune fully dependent on it in case it fails.
Got more UK results on pump fuel at 1bar on a street port. This time on a G30 770 1.01ar. SAS 3" exhaust SAS turbo kit with a Garrett G30-770 1.01 AR Treadstone front mount Fast reacting IAT from a chap on Facebook GM 3-bar map sensor from Banzai ChaseBays AST delete AEM water temp, oil temp & AFR gauges Full fuel kit from FFE (ID725 & ID1700, FFE rails, FuelLab FPR etc) IGN-1A coils and Walbro 450 kit from IRP Stage 3 Competition Clutch & Ultra Lightweight flywheel (4.39kg) Greddy elbow (of course!) and Greddy OLED boost controller
The owner mentioned the tuner requested more dc i.e.more boost but unfortunately the car didn't want to hold any more than 1 bar! The tuner concluded that's all the turbo could flow. Slightly strange as they expected the turbo to do better and were hoping to run 1.3/1.4 bar. Final results holding 1 bar boost.
422 fwhp - approx 360rwhp.
Owner mentioned he is happy with the way the car drives as it picks up very quickly yet doesn't blow the tyres off!
This run is going up hill so corrected would be 8.12, which is very similar to what i ran around 350rwhp on the G35 1050 at 12psi which was 8.14s.
Thanks. Obviously it's all hypothetical for my case.
On those charts, it shows the G55 being more efficient than the similar sized/named gen2 version. I remember seeing this similarly on Rob's video where he upgraded the turbo on the turbo tommy 3 rotor car (I guess I can't really refer to turbo tommy anymore given the entire car has been redone by now haha). I can't remember the model numbers at the moment, but basically able to go down a size and have the same flow, or stay the same size and increase flow.
I recall both David's and robs being capable of well over 1k horsepower, and I need to go refresh myself on reading the charts, but does that all mean you could go down to the G50 and not have the car feel like it's stagnating at the top end? Or could you go even smaller like a G47, would it flow enough but require higher pressure ratio, but due to the smaller turbine the emap would climb too much at the higher rpm range and choke out?
no, the issue is low boost pressure for PP in the 1 Bar range.
Turbos in this range are generally intended for higher boost, as those maps indicate. So you have to factor this in when looking at the ~1.8 - 2.2 PR vs WHP flow requirement on the compressor map. Even though in theory 1000 whp on a 4-R is equivalent to a 500 whp 2-R and on low boost, I still wouldn’t want to be pushing it out to the the lowest efficiency island. Though it likely would be ok under those conditions unless something else goes out of spec.
the other trend you may notice is that as the inducer diameter increases the map highest efficiency island tends to move up and become narrower, and also the same for the lower LH corner for surge consideration as well. I had to bounce around between 10 or 12 frame and inducer G-series sizes to focus on the G55 above. There were a few others to consider, but all larger in my own assessment.
When Rob Dahm did 1000 whp on the 3-R there was some discussion in here prior to the dyno run about turbo size. and I recall Dave M. suggesting a much larger turbo size. I think he was considering low boost in that assessment, but it wasn’t a PP. The 1000 whp run was in the 32 psig boost range, which was in the range of the turbo used, though with highish emap.
It overran the turbo past the shaft rpm limit on the RH side of the map to make 1050 whp as I seem to recall. Because the G-series turbo used was still over 70% efficient there, but the aluminum compressor impeller is limiting running past that point due to the centrifugal force of such high shaft rpm about to tear it apart.
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Good point about PP. I'm mainly thinking about side ports. And comparing to a 500whp 2 rotor is exactly what I was doing in my head so funny you mention it.
I should probably change the idea to 800whp, because if I were to ever do it I want something that stresses the motor very little, but still makes enough power to make swapping from a 3 rotor worth it. A 2 rotor with 400whp is a pleasure to drive and is typically reliable and long lasting, on pump gas. Maybe a little water injection doesn't hurt.
08-16-23, 03:51 PM
