Budget 998 Turbo Build
Turbo Mini Forums

I hope it's got a red undercoat for the extra 10% power.

In the 13's at last!.. Just

Is the cam the MD274?

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

You sneeky bas....
I suspected it all the time, but you wouldn´t tell

Now.. you did talk about the scatter-pattern cam. so why not the MD274SP ?

If i have more toys than you when i die, I WIN

The MD274SP has a much lower LSA on both inner and outer cylinders, 108/106.

Edited by Paul S on 18th Nov, 2011.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

the 274 is a good road cam, I know a few people who have had good results with it on non injection normally aspirated engines. Under rated if you ask me It netted me 95 hp 100lbft on the 1400 on its last outing, which is more than most 1380 286 cammed engines

Clocked it from you saying you had a longer exhaust duration then inlet. Coupled with a low overlap to bring the boost threshold down. 274 is the one that sprung to mind.

Short engine assembled OK:



Only issue is 0.010" crank endfloat with new std thrusts. So I'll have to change them later. Moss list a set at 0.003" oversize. I'm assuming that is each one?

Stuck now as I can't find any cam followers in the parts bin.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

just turn a bit of metal up on the lathe to .810 to time the cam in, you can drop the followers in later.

a 3 thou oversize set is 1.5though per side,

Thanks Joe, that's a good idea.

I've just found a couple of +0.005" thrust washer sets on ebay and bought those, so thrusts should be sorted and on optimum clearance.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

The new thrusts have arrived. I can confirm that each thrust washers is 0.005" thicker, so I just need to use the thicker ones on one side.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Looking good!
(wish I had more time to make some progress with mine )

Is the idle ok with the 276 cam in the 998?

Are you planning to use the same set up for the cam sensor as the Ti?

The cam is the MD274 not the 276, they are significantly different, a lot less inlet duration on the MD274 at 248 degrees. Idle is fine on the Ti.

Cam sensor will be a modified dizzy body, a bit more cut down than the last one. I have the bits of dizzy on my desk and trying to make a decision on which hall sensor to use.

Edited by Paul S on 23rd Nov, 2011.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

On 19th Nov, 2011 Paul S said:
Short engine assembled OK:

Dazed and Confused....

Nope.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Thought I read somewhere this was done to prevent bolts 'eating' into softer material of CM strap.

Dazed and Confused....

Well, taking into account the compressive strength of the materials and the actual clamping area under the bolt head, I'm inclined to think that if the standard caps do not need washers, then the strap does not.

Anyone ever seen any evidence of straps deforming due to the bolt loading?

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Just for the record, I was just curious, obviously you know what you are doing.

Found were I read the hardened washer bit:
http://www.turbominis.co.uk/forums/index.p...&tid=4544&fr=50

PaulH:
" Get that caps machined correctly use the right bolts and some hardened steel washers and get on with it."

Dazed and Confused....

I'm not sure if it's the same on the 998 (long time since I had one apart) but on the 1275, the heads of the standard bolts are one size larger than would be normal for the thread size.

The MiniSpares centre strap ones weren't.

I junked them anyway as they were the rogue 3 stripe ones but the bolts I got from Carl were also one size larger on the head.

It may not be much but it does increase the clamping area and hence reduce the point loading.

So no eveidence, but it does seem a good idea if the bolt heads are smaller than the OEM ones (can't tell from your photo).

Schrödinger's cat - so which one am I ???

The bolts are the 6 stripe ones from Minispares and have a superior clamping area to the standard bolt. 5/8" AF, same as the standard bolts.

Standard bolt is on the left:


The inner ring visible on the standard bolt is actually a recess.

The MS bolt is dead on 11.5mm diameter under the head, so I've made the hole in the strap 11.5mm with a minimal chamfer to maximise the clamping area.

Edited by Paul S on 23rd Nov, 2011.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

The standard A+ bolt is a special bolt with an undercut head. The slots in the top f the head combined with the undercut allow it to elastically deform as the bolt is torqued down. This deformation is designed in to act as a kind of self locking mechanism. Anyone who has stripped anA+ motor will know that it takes a great deal more torque to 'break' the bolts loose, than it did tightening them. I would coose those type of bolts over any other when I can.

The same type of blots are found on the 8.4" drive flanges for the same reason

Sorry must learn to read!

Didn't even know they did a 274 - just going off the yellow book!

This looks like an ideal cam for the 998 though.

Builds getting there. I like the idea of a small bore turbo aswell actually. Possibly bring the cost of insurance down? Just out of interest why are you using piston buttons? Never seen them before.

i got nothing but time..