Project Evo IX Part 7: Cosworth Rocks!

Project Evo IX Part 7: Cosworth Rocks!

By Mike Kojima

When we last left off on Project EVO IX, we had increased the capacity of the fuel system with larger injectors and improved the flow of the intake and exhaust tract with a bigger throttle body and less restrictive intake piping.  We also did some ECU tuning to produce a significant jump in power.

Read More About Project EVO IX here!

Project Evo IX Part 7: Cosworth Rocks!
We selected Cosworth M2 MIVEC cams for Project Evo IX.

For our next round of tweaks, we obtained a set of Cosworth M2 cams for the MIVEC variable cam timing version of the 4G63 found in our EVO IX.  Camshaft design is very tricky with many of the aftermarket offerings not being engineered to control spring surge induced valve float. Consideration of higher order harmonics is unheard of and valve spring tension is simply increased to enable higher revs and more aggressive profiles. Cosworth being an engineering intensive company considers this stuff and uses this as consideration in their profile design.  Most of the aftermarket cannot compete with Cosworth engineering's prowess and their extensive validation testing in design optimization.

Project Evo IX Part 7: Cosworth Rocks!
To ensure valvetrain stability to 8000 rpm, we used Cosworth single high rev springs.  The springs feature a conical shape to give them more coil bind height in less space.  We WPC treated our springs for better fatigue life and cooler running.

Fighting spring surge is always an issue with high performance engines.  The spring's natural frequency must be matched to the acceleration of the cam's ramp angles to avoid exciting the valvetrain which can cause surge. If the system is engineered correctly surge can be controlled passively by design and a lower tension spring can control valve float.  Lower spring tension means less friction, more power and less wear.  Having an engineered spring/cam system means that it's not a good idea to mix and match components between manufacturers.

Project Evo IX Part 7: Cosworth Rocks!
Our stock camshafts had heavy wear despite their being a roller design and our engine having relatively low miles.  Because of this wear we decided to WPC treat our Cosworth cams before installing them.


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Wednesday, March 02, 2011 8:35 PM
Great article as usual Mike.
Do you know if Cosworth has a M3 camshaft available or is the M2 the biggest they offer? Maybe Eric can chime in.

I would shit my pants removing those keepers from the valves and not drop them in the engine. Howard must have had super steady hands.

As far as the ARC oil cooler, great stuff, too bad the company filed bankruptcy just yesterday. I hope they will find a way to come back (much like Greddy did few years back).
Thursday, March 03, 2011 1:12 AM
I'm not sure I would have the balls to try and remove the valve springs with the head still on the engine. Nice power bump though with the Cosworth cams though, proper engineering wins every time.
Mike Kojima
Mike Kojimalink
Thursday, March 03, 2011 5:23 AM
We are going to run the M3 cams later when we do some more work to the engine.

MP it is routine to change valve springs like that. I have done it many times myself and it's not that hard and doesn't even take that long with the proper tools.
Thursday, March 03, 2011 5:48 AM
Interesting, I've never done it except with the head off the engine. I guess I never really considered it either for fear of dropping a keeper down into the engine. Need some NdFeB magnets ready to catch them. :)
Eric Hsu
Eric Hsulink
Thursday, March 03, 2011 8:02 AM
For on car spring removal and installation, this tool or something like it is the best. I have an older, made in the USA version of this tool, but this Lisle tool looks like it does the same thing. One end of it, you simply place over the locks, smack the tool with a hammer and the magnetic chamber catches the cotters that would otherwise fly away uncontrollably. To install cotters, place the cotters inside the tool (comes with different size holders) and push on the tool to install cotters. The only problem is when you have a heavy valve spring it may take a couple guys to get the cotters on. But then again if you're installing something that heavy, you probably should not be installing it on a stock head anyway.

I wonder if Nisei has ever flowed their core and end tanks. That kind of mid-90's HKS GT style end tank doesn't flow all to well since the plates flowing the charge are heavily shrouded at the top of the core. HKS doesn't do it anymore either. I'm NOT saying that the Nisei core does not flow well. I am simply posing a rhetorical question.

TUBE & FIN FOR LIFE!!! Mike, what is the exact weight difference between the core assemblies?
Thursday, March 03, 2011 11:26 AM
The right tools DO make all the difference! what you save in not buying tools you spend in time and on broken components/tools. I'm slowly starting to learn that fact....
Thursday, March 03, 2011 11:42 AM
Great timing on the article! I'm planning to do cams w/ springs and retainers in my eclipse here in the next few weeks, once I get some free time between nasa events.
Thursday, March 03, 2011 1:12 PM
Shoot, back in the day I used to feed (new) 1/4" rope through the spark plug hole with piston at BDC, then rotate the engine by hand until the rope was compressed against the piston and valves. Shaved a few hours off valve stem seal repairs...

As for the intercooler, congrats on filling the grill, but give me the XS any day... Those Nisei end tanks are far from ideal and I'm not at all surprised that you were unable to find any gains.
Mike Kojima
Mike Kojimalink
Thursday, March 03, 2011 4:50 PM
I did not weight them but the Nisei seems to weigh about 2x as much as your IC.
Friday, March 04, 2011 7:30 AM
It's nice to see that the cams gave gains through the whole RPM range. Usually, increased duration cams can lose power down low to gain power up high. Some of this steady gain is also the fact that Mitsu uses a fairly aggressive cam to start with. (for stock) I believe the stock duration is something like 260*. (i'm probably wrong)

Also, the tapered valve springs; do they act like a progressive spring as well? Meaning, do they compress easily to begin and then get stiffer? I understand the binding benefits, but was curious if they were progressive and what the gains of a progressive valve spring might be.
Eric Hsu
Eric Hsulink
Friday, March 04, 2011 3:11 PM
Yes, beehive springs act like a progressive rate spring. Not only can we adjust the progressive rate more accurately, but we can also adjust the spring's resonant frequency more accurately which allows us to eliminate spring surge...at least with Cosworth cams. With the top of the spring being smaller in diameter, we can also use the factory Mitsubishi retainers which are lighter than anything commercially affordable including Ti. We can save weight with the factory retainer and with the beehive spring requiring less material. This can also reduce the tendency for surge and float.
Eric Hsu
Eric Hsulink
Friday, March 04, 2011 3:13 PM
I should also add that there are applications where you need the brute seat pressure only available from dual or triple valve springs. The disadvantage of a beehive is that you cannot run inner springs so you will rarely find a beehive spring in an all out race engine.
Friday, March 04, 2011 11:28 PM
Eric, is the Costworth intercooler a tube and fin type?
Mike Kojima
Mike Kojimalink
Saturday, March 05, 2011 3:45 AM
This is why mixing and matching valvetrain stuff with cam stuff from different manufactures is a bad idea. No Cosworth cams with BC springs for instance.

At least for engineered cams like Cosworth. Most aftermarket crap just jacks the seat pressure and the cams are designed as morphed copies of the stock opening profile or copies of something else.

The Initials company is like this.
Saturday, March 05, 2011 7:18 AM
Damn it! My XS Engineering intercooler took a hit on the freeway and I wanted another one. I'm not a fan of bar and plate either.
Eric Hsu
Eric Hsulink
Saturday, March 05, 2011 8:11 AM
Czubaka: no, Cosworth performance parts cores are currently bar and plate cores, but they are lighter than most other bar and plates. They are designed with thinner plate material and thinner fins that makes them lighter than most other industrial heat exchanger based or diesel cores.

We had a tough time finding a supplier to make tube and fin cores to our design and specification. It requires a lot more tooling to manufacture tube and fin type cores. The end headers, tube manufacture, tube brazing, and even oven fixture all require custom tooling. For a stacked plate/bar and plate core all you have to do is literally stack the plates and fins, slather the core with braze, and cook it in the oven. Very little if any tooling is required for the manufacture of a bar and plate core. We're working with some potential tube and fin factories now however.

Laurence: I spoke to Troy @ XS. They can still build you an EVO core if that is what you need. They have a few end tanks left over he said. You can hit him up at sales at xs-engineering dot com. Let him know I sent you.
Matt Dennison
Matt Dennisonlink
Saturday, March 05, 2011 12:38 PM
Even though you didn't gain much with the Nesei, but wouldn't the larger core help keep the inlet charges cooler during aggressive driving...?
Tuesday, March 08, 2011 7:48 AM
Eric thank you so much!

Matt, any intercooler is going to cool boost. But once it soaks up that heat, how quickly can it get rid of it? Pound for pound, cooling square inch to cooling square inch, those big bar and plate cores do not shed heat as efficently as a good tube and fin core will. Yea, big ol' bar and plate cores can soak up a lot, and that's great for those that overtax a turbo for sort bursts, but why hang a big ol' hunk of aluminum off the nose of your car if you don't have to? Yea, people do it all the time, but why not do it right? Match the turbo to your true power goals and make efficient boost. If your making efficient boost, you don't need that big ol' heat sink. A quality tube and fine will soak up heat just as well and exchange it quickly so you can continue with that "aggressive driving."
Wednesday, March 16, 2011 8:59 PM
I was wondering if you were going to consider water injection. Looking forward to the next instalment.
Wednesday, April 13, 2011 9:21 AM

I am considering Cosowrth M2 and M3 for EVO VIII, with HKS 7460 GT turbo.
I am under impression that the M2 is a midrange cam with nearly no sacrifice in spool and that M3 (require springs, that is fine), boost futher midrange and a little top end, compared to M2.
Finally, I think that it is reasonable to expect 25-30whp on Mustang dyno gain from cams, overall, on 91 Octane at peak boost pressure about 23-25psi.

Can you please offer me advice, which can would you chose, and why?
What difference will result between the two?
I am expecting them to idle lopey, which I am willing to tollerate as long as spool is minimally sacrified if at all, and midrange is boosted.

Thank you
Eric Hsu
Eric Hsulink
Friday, April 22, 2011 4:26 PM
Sorry for the ultra late reply.

I know nothing about the 7460 GTII turbo, but it would generally depend on your exhaust backpressure situation. If you're running an open exhaust, the M3s will shine from 3500-8000rpm. If you're running a cat and a choked down or baffled rear muffler, the M3 will probably only make more power from 6000-8000rpm and the gains will be lesser.

In either case there the is some loss in power at WOT under 3500rpm (M2 vs M3). Some people complain about loss in engine response with M3s driving around town, but that shouldn't be the case. Its the tuner not addressing part throttle MIVEC, timing, and fuel maps thats causing the loss in part throttle response.

So to summarize if you have a shitty exhaust I would probably stick to M2s. If you are running a good exhaust, then I'd go with the M3s. On 91 octane its exhaust backpressure that affects the amount of timing and cam advance you can run. The more you free up the back pressure, the more agressive the engine tuner can get which really allows the M3s to shine.

Good luck. I hope this helps. You can message me if you have further questions.
Monday, August 01, 2011 9:18 PM
Where did you guys end up finding a Nisei intercooler? I've been trying to get a hold of them forever to get one but it seems they are out of business.
Mike Kojima
Mike Kojimalink
Monday, August 01, 2011 9:26 PM
Maybe they are by now. Now I have to find yet another IC....
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