Nomenclature is very interesting...

People keep referring to the "Cosworth kit", but is the package really from Cosworth? Doesn't Cosworth just do the modification to the stock head? What other parts in the kit that is being sold by M7 actually have been fabricated or worked on by Cosworth? If Cosworth were to really do a kit(s) for the Mini, what do you think it would be, and what do you think it would cost?
Some people seemed to have steered this thread towards a "shootout"/battle between Cosworth and JCW. If folks are going to do a spin on the facts, they should at least get their facts straight---

 

The cost of a new turbocharger is easily over a thousand dollars. I'm not sure what the cost of repairing/overhauling the one used in the TC kits, but that's a HUGE chunk of change in my opinion. The other thing I was wary of is that the extra boost on the stock [ie, ROUGH] head is more likely to cause failure than the hotter, less-pressurized boost is on my new head. At higher boost levels, I saw gaskets going, and being as how I don't trust myself to tear apart my engine to fix the thing, that is a costly exercise to reset the head. Plus, the last thing I wanted was a warped head. Yes, a WARPED head. It's happened at high boost levels [with nitrous, if I remember right]. Bottom line, I can't afford that habit right now. Thus, I 'settled' for 200 whp. I'm happy!

 

the main gain from twincharging is to shift the boost production to the less parasitic turbo and to fed the sc with higher intake pressure, lessening its load and heat. the result is you can run the same 19psi boost (as the 19% pulley) and gain another 50whp. the combustion pressure is the same and the charge temp is lower. There is actually less strain on the head and gaskets.

 

I haven't seen a 19% make 19 psi boost ?!? I thought I saw a 17.5 once, but not 19 (!!!). I've never run 19% myself, though. Anyone?

 

If you are truly happy with your mods & 200 whp great... No need to justify why you chose not to go turbo. At the very least it is changes the under hood environment drastically. This won't appeal to everyone (or their dealer)

The colder boost a Twincharging system makes would be less likely to cause failure than the hotter boost from a 19% pullied car (on either head). A large % of the increased PSI (as seen on boost meters on pullied cars) is due to heat/pressure generated by spinning the S/C faster... 16 or 17 PSI from a 19% or smaller pulley & higher engine red-line is not equivalent to 16-17 PSI from a Tubo/Supercharger configuration that spins the S/C and engine at lower rpm. The T/C configuration boost will be cooler and thus more dense with oxygen. Fitting more oxygen molecules into the combustion chamber per cycle is what makes power. If you're filling the chamber with hotter less dense air power will not be as great. This is how and why the T/C option creates so much power.

On the safety side of things... Colder boost affords a number of advantages: Less fuel required (for the purpose cooling the chamber) and no need to increase timing. Both of which are concerns (detonation) when the supercharger is spun faster & boost gets hot. Less fuel for cooling also helps milage.

BTW turbo/supercharger configurations & boost from them is not the same as boost from nitrous. You've made a connection which doesn't exist. Warped heads due to nitrous is a different discussion. Bringing it up here only muddles things.

EDIT: Thoughts re: turbo and maintnance... I don't know what the scheduled maintnance or lifespan is for new turbos. I think I heard that the MINI supercharger is supposed to be good for about 100,000 miles
(stock pulley & redline). It seems to me that if you aren't pushing the turbo hard and your spinning the s/c less than stock you ought to get better life out of each (and better than either on its own) theoretically speaking.

 

I doubt I'll ever be close to one, I live in the North Pole, almost neighbor of Santa, I'm about 400 miles North of the Canada/US Border of Montana.

 

I read all the posts on this thread and at this point I'm almost positive that if the quest was not looking for who gets the most power but try reaching the same power and torque between a Cosworth kit and a twin charge there wouldn't be any reliability issues with either one.

With the Turbo, you might eventually have to replace the Turbo but with the Cosworth kit or any smaller supercharger pulley, you may have to rebuild the SC sooner.

As for burnt pistons, if you keep your boost in order to make the same power as the other tuners, I wonder if it would happen?

I think the biggest problem here is trying to get too much out of the Turbo kit and since you can get more, that's what cause the problem but I could be wrong.
I have more experience with V8 and turbos than 4 cyl. and I know the cost of V8 turbocharge is always more expensive because you need to do the bottom end in order to lower the compression but Turbo once done will give you the most power for the money.
Building a 415 cu.in. out of a ZR1 will give you 650 hp for about $22k and about 12 mpg, but a 368 TwinTurbo will give you about 750-800 hp for $42k and 24 mpg on the highway, but here's the catch, the 415 will have to be rebuilt after about 50k miles while the twin turbo will last you twice as long if you only drive it like a 415, so if your plan was to keep it for 100k miles they both cost the same in the long run.

So what's my point? if you are to spend $5k on any tuner package, and keep it in equal hp level, I bet reliability would be pretty damn close but if you want to make more power, you should spend more money and that means, if you want 300 whp and can't afford to spend more than $5k, you shouldn't get 300 whp.

For my own taste, I still think M7's package is all I need, after all, it's a convertible that I bought and if I want to go faster, I'll take my other ride, but I still enjoy this discussion because I'm still learning from it, I don't like when it gets too personal and start to get a little out of hand, but there is still some good information coming while I'm waiting for those 0-60 numbers now that I have the dyno numbers.

My wildest dream right now would be to tune the boost of a twin charge car on a dyno to make the exact same power as a properly tuned and maxed out Cosworth car and have equal power, equal weight and have both car following each other all day, have a few races and check who uses the most fuel, and see who would be the quickest from a dead stop, then from a rolling start and even 70-100 mph, now that would be a fun day.

 

anything you can do to reduce the contribution of the SC and get the same boost will net a gain due to less heat and less hp draw by the SC. At 14k rpm, the Eaton is eatin' 40hp, so one trick is to reduce the rpm of the sc vs engine rpm, using, guess what, the stock pulley, (or larger!). There are probably quite a few secrets the twincharger boys have come up with, but the above gives you an idea of the approach.

 

Here’s some partial peak boost trivia from the data log. The peak number was taken at a point where the TB was still WO. Atmospheric pressure for the day was measured at 29.76 HG. As far as I can tell Dave Chen had the smallest pulley at 17%.

Dave Chen 16.11 lb. @ 6696 rpm, IAT 174 F
Bob Nigbor 15.75 lb. @ 6878 rpm, IAT 154 F
Cos Bill 13.00 lb. @ 6944 rpm, IAT 127 F

 

I don't believe in theses calculations you can just use a static figure like 29.76 for all instances.

In looking at Andy's figures I think the correct formula for calculating Boost in this instance is Manifold Air Pressure(column P in Andy's file) minus Upstream Manifold Air Pressure(column Q in Andy's file)divided by 68.95.

The cell formula would be something like =(P4-Q4)/68.95.

If I apply this formula to the numbers I have from Andy for all my runs the boost makes sense. About 0 at idle and 14.5 or so at full throttle:


This is what I get from my best run.

Engine Engine Inlet Manifold Upstream Corrected
Speed Coolant --Air ---Air --Manifold
------Temp -Temp Pressure Pressure "Boost"

2102 86.25 33 540.79 525.19 --------0.23
2140 86.25 33 598.36 577.89 --------0.30
2253 86.25 33 1487.39 955.5 --------7.71
2385 87 33 1626.18 986.77 ----------9.27
2590 87 33 1656.51 986 -------------9.72
2798 87 33 1666.54 983.77 ----------9.90
3015 87 33 1647.1 982.01 -----------9.65
3224 87 33 1654.71 979.92 ----------9.79
3437 87 33 1679.36 977.8 ----------10.17
3654 87 33 1704.55 974.83 ---------10.58
3876 87 33 1731.25 972.23 ---------11.01
4087 87 34.5 1753.37 969.41 -------11.37
4302 87.75 34.5 1763.33 966.26 ----11.56
4507 87.75 36 1775.93 962.27 ------11.80
4725 87.75 36 1786.88 959.89 ------11.99
4939 87.75 38.25 1809.81 954.69 ---12.40
5151 87.75 38.25 1831.6 951.32 ----12.77
5379 87.75 38.25 1856.42 946.71 ---13.19
5607 87.75 40.5 1872.61 941.47 ----13.50
5848 87.75 40.5 1870.6 934.69 -----13.57
6076 87.75 44.25 1865.47 926.89 ---13.61
6296 88.5 44.25 1867.92 922.57 ----13.71
6510 88.5 48 1875.69 916.57 -------13.91
6730 89.25 48 1883.38 912.03 ------14.09
6944 89.25 52.5 1905.2 906.57 -----14.48
7151 89.25 52.5 1897.73 872.25 ----14.87


That 14.87 boost number also jives with other data logging done in the past on this car.

[edit] I think you can make out the numbers, I couldn't get the formating right.

Bill

 

In relation to twincharging. Is engine break-in related to current HP at all? Like say you took the MINI's 1.6L, and had 168HP, and broke it in with that figure, and later on (25k miles or so) added a +100HP T/C kit. Or if you took the MINI at brand new, and broke it in with the +100HP T/C kit from the get go, would the engine be better suited for the extra HP by breaking it in off the bat? Or does it not matter the engine's current HP when breaking in a engine, with regard to future planned HP boosts. Hope that made sense =)

 

That’s an interesting way of looking at the boost calculation Bill. Here’s my perspective, at no point while the car is running does the UMAP show positive pressure values they are all below atmospheric pressure readings. Atmospheric pressure is true zero and anything added to that is called boost. So, the formula you used does not have a true zero it is only an interval scale and not valid for this measurement. There is also an inverse correlation, the higher the rpm the lower the UMAP reading (lower pressure).

 

Hey Bill,

As I previously mentioned in discussing the beta Bim-Com log that I sent to you and regarding my added column in the spread sheet that converted millibar to psi, one needs to subtract atmospheric pressure, not the upstream manifold pressure. I had checked this with Andy, and he explained to me the appropriate calculation used atmospheric pressure, not the upstream manifold pressure. K-huevo's explanation also is spot on.

BTW, no one has answered my post regarding warranties and what work was actually done by Cosworth in kits similar to that on your car. Perhaps you could shed some light on this. Thanks...

Anyway, keep motoring and having fun...

 

BTW, no one has answered my post regarding warranties and what work was actually done by Cosworth in kits similar to that on your car. Perhaps you could shed some light on this. Thanks...

Anyway, keep motoring and having fun...
__________________
Bob W.

Bob I didn't realize you were that serious in purchasing more products from us. I'm glad to see the flywheel is still working out well for you BTW. If you like feel free to give Peter a call and he will be overjoyed to answer all your questions .I am sure you still the number but if not it is 562 608 8123. As everyone knows he is only a phone call away at anytime to answer any of these questions or just talk " Mini " in general .

Randy
M7 Tuning

 

When i stopped by Helix for a pulley a few months ago i got a ride in the TwinCharger. We go out onto some nice long straightaways and the car absolutely flew. The traction control light was flashing from 1st to almost the end of 3rd gear. It certainly made my car's improvement with the new pulley seem much less drastic. I have been wanting to upgrade to the kit ever since and hopefully when out of college will be able to!

 

Absolute pressure in the manifold will tell you the power potentail (if you know the temp). The pressure difference across the SC will tell you how well it's working (if you know the temps).

I think boost referenced to atmospheric is easier, as it only takes one guage, and it also matters more when approaching the limits of the motor.

Matt

 

maxmini...
Bob I didn't realize you were that serious in purchasing more products from us.



I'm glad to see the flywheel is still working out well for you BTW.

Now that's a real can-'o-worms that's probably best left unopened --- enough said

Motor on....