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Old 10-23-2007, 08:35 PM   #1
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Questions?? O.S. Speed .21VZ-B V-Spec ......Alloy Head or Magnesium??

Hi all,
I am looking at buying an O.S. Speed .21VZ-B V-Spec motor and would like to know which would be the better version (Alloy or Magnesium).
Does anyone have either of these that could provide constructive feedback?
Please provide an explaination for your suggestion and not just vote for one or the other.
Thanks in advance.........Dave
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Old 10-23-2007, 10:53 PM   #2
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One weighs more (al) and one weighs less for a lower center of gravity (mag).......

One disapates heat away from the engine better(AL) and one doesn`t(mag)........
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Old 10-23-2007, 10:54 PM   #3
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oh yeah and the mag head bends easier
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Old 10-23-2007, 10:54 PM   #4
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The al is around $50 cheaper
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Old 10-23-2007, 11:24 PM   #5
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I ran the original speed since july but with an aluminum head from one of my other V-Spec engines. I heard the temps are way high running the mag head so I ran with the aluminum version from break-in. The minor weight saving will be negated with dirt build-up as you run. The mag head sure makes for an expensive paper weight. I've had 4 V-specs, an Ebmod and then the speed. All are great with slightly different power delivery between them. There isn't a huge difference in power. The difference can be made up if you get a better drive out of a turn or have a slightly better setup. I remeber at our CORCS finals a guy with a Werks B7 pro walked the speed engine every time. My next engine will be a Axe Rossi Cobra Evolution X1. However, I'll have a Speed Al ready as backup since they are the most reliable engines.
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Old 11-03-2007, 03:04 PM   #6
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Thanks for all the feedback guys

Kind regards.........Dave
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Old 11-04-2007, 11:25 PM   #7
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hey Dave you gettin ready for the Nats aye

hamilton maybe running a meet on the 18th of december with the track changes completed heres a link to the nats web page for you

http://www.hrccc.co.nz/2007_nationals.php

also keep an eye on

http://www.franktonmodels.co.nz/phpBB2/index.php

for updates on possible race meet on the 18th nov

we had a run yesterday and the track changes aren't bad little bit tight maybe. shame we got rained off I was the only buggy to do a 34 sec lap and i'm still running in the motor

with the rest of the changes they're expecting about 39-43 sec lap times so it should be a good meeting.

now back to topic -Ali head for sure for the extra price of the mag head (especially when your talkin NZ dolars) any performance gain isn't noticeable

see you in December

Adrian
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Old 11-16-2007, 12:52 AM   #8
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Hiya Adrian,

Wont be able to make it for the Nats warmup this weekend. I'll have to get some inside knowledge on setups and tyres as the three 10 min organised practices is not going to be much time to get to grips with it, any tips will be gladly accepted. .

I have just managed to organise time off work for the Nats so will now be able to send off my entry.

Just checked out the photos of the Hamilton track, http://www.hrccc.co.nz/2007_nationals_pictures.php Wow...it's looking very good, cant wait to get out there.

Looking forward to catching up.

cheers.....Dave
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Old 11-16-2007, 01:35 PM   #9
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Quote:
Originally Posted by Toycar5 View Post
I ran the original speed since july but with an aluminum head from one of my other V-Spec engines. I heard the temps are way high running the mag head so I ran with the aluminum version from break-in. The minor weight saving will be negated with dirt build-up as you run. The mag head sure makes for an expensive paper weight. I've had 4 V-specs, an Ebmod and then the speed. All are great with slightly different power delivery between them. There isn't a huge difference in power. The difference can be made up if you get a better drive out of a turn or have a slightly better setup. I remeber at our CORCS finals a guy with a Werks B7 pro walked the speed engine every time. My next engine will be a Axe Rossi Cobra Evolution X1. However, I'll have a Speed Al ready as backup since they are the most reliable engines.
Yeah... so skip those and buy the B7 Pro for less money!
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Old 11-20-2007, 04:52 AM   #10
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Busy running in my Speed with magnesium head.
What I have noticed is that the magnesium head is a better conducter of heat than the aluminium. I think some guys confuse this and say that it runs hotter.
I can definitely see the difference. The mag head heats quicker and cools quicker. I dont find the engine running higher temps generally.
The important part is the rate of cooling.
Definitely has an advantage over the stock aluminium.
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Old 11-20-2007, 04:59 AM   #11
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The heat does not get transfered from the block to the head thats the problem with the magnesium head.Sure the head is cool,but feel the block it is wayy hot.Its a sick engine i love mine with the aluminium head.
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Old 11-20-2007, 03:16 PM   #12
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Well all I can say is Ryan Mayfield is still using the mag head and is having great success with it so I'm sticking to my mag head.
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Old 02-11-2008, 05:00 AM   #13
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I think that the issue with the mag head is being missunderstood, Magnesium is a better heat conductor than aluminium. Therefore, it will dissipate heat in to the air faster than an aluminium equivilant. The heat from the block is transfered to the head at same rate (as fast as the alloy block will allow) as any other engine, BUT, the head will transfer it to the air more efficiently than alloy so this is why the head stays cooler.....

Aircraft piston engines use mag heads for the same reason.....
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Old 02-11-2008, 05:31 AM   #14
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The only problem I've seen is that the Mag. head breaks easier. I've seen several with broken cooling fins.
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Old 02-12-2008, 12:39 AM   #15
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I think you are wrong about the magnesium head transferring heat better than the alloy head, if you look on the os site at the v spec with the alloy head it says the the alloy transfers heat better than magnesium.
Wayne Walker from Australia who is a Mugen factory driver has been running the ninja MRT engines both on and off road for the last 9 months and has replaced all magnesium heads with the latest MRT alloy heads. Mugen sent new alloy heads to the Australian distributor for all MRT motors sold, why would they do that if there was no problem.
Wayne won the New Zealand Nationals running a Ninja MRT with the new alloy head where all other drivers running MRT's still had the magnesium heads and most had tuning problems because the engines run to hot. I hope this helps with your decission.

Barry Walker
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