Printable Version of Topic

Posted by: r_towle Sep 9 2013, 08:34 PM

What is a street able motor (valve train) set of materials that could sustain 7k rpms ?

So, what valve material, spring materials, push rods, lifters etc.

No ceramic lifters unless they are out on the market again.

Rich

Posted by: kg6dxn Sep 9 2013, 08:44 PM

Does it have to be a T4?

Posted by: r_towle Sep 9 2013, 08:48 PM

Yes

Posted by: worn Sep 9 2013, 09:11 PM

I wanna hear this too. I have a second case after all.

Posted by: Mark Henry Sep 10 2013, 05:28 AM

"Street-able motor", 7000rpm and type four don't go together.

I know someone will disagree with me

Oh..... and I have an extra set of ceramic lifters

Posted by: rick 918-S Sep 10 2013, 05:48 AM

Start with a shorter stroke crank. I would research adapting roller tip lifters from American hot rod engines. Same with the rockers. Lots of machining and research.

Posted by: Jake Raby Sep 10 2013, 06:08 AM

The engine I built for the Mighty Spyder in 2005 coupled a 69mm stroke with a 105.7mm bore and twin plug LE 230 heads and a RAT roller camshaft and lifters. It made power to 8,500 RPM and is very street able. Peak power was 265HP.

12:1 CR and twin plugs (runs fine on pump gas) were the key at making this engine well behaved enough for street service, while making a ton of gross power at the top end of the RPM range. The roller cam builds a ton of torque through better chamber filling at low valve lift values.

EFI also helped a ton with direct ignition as it gave better resolution for tuning the flat spots out at low and mid-range throttle positions and MAP levels. Carburetors would have been very difficult to tune for street service with this combination.

The owner is now in his 70s and drives the car on the street all the time, he also competes in hill climbs and all other sorts of track activities, too.

Posted by: Mark Henry Sep 10 2013, 06:58 AM

By just looking at Jake's spec list on that engine and knowing some of the costs involved, I'd bet a /6 would be cheaper.

Posted by: sean_v8_914 Sep 10 2013, 07:45 AM

if velocity is defined and force is the entity to be managed, that only leaves mass as a variable
reduce the mass of reciprocating parts

Posted by: stugray Sep 10 2013, 08:54 AM

So Jake, I assume that the FA20 motor in the Subaru BRZ gets it's 7500 RPM redliine because of the DOHCs?

And possibly the fact that it is a "square" motor (86X86)?



In my other thread, I posted a motor for sale for only $3k that I thought you could have some fun with.

Stu

Posted by: DBCooper Sep 10 2013, 09:06 AM

Square actually makes it harder to get high revs. Jake was describing an oversquare engine, bore a lot larger than stroke, so lots easier to buzz. The square ratio makes for a more balanced motor.

That's a beautiful engine, by the way. Look at the size (and number) of main bearings, the little tiny coated piston skirts, those beefy rods, long rod bolts, big thin and smooth counterweights. That's nice.

Posted by: Jake Raby Sep 10 2013, 11:55 AM

I have a similar Suby combo now with a 104mm Nickies bore size and a destroked crankshaft. Its much cheaper to build than the Mighty Spyder was.

I have only built one engine that cost more to work with than the Mighty Spyder and it was a Fuhrmann 547 4 Cam Carrera.

To build a hi-RPM T4 cheaper use a 66 stroke crank, couple it to 105s and spend as much as possible on the heads, then optimize them to the camshaft and valve train.

Posted by: DBCooper Sep 11 2013, 07:40 AM

There it is, the only material you need is cubic money. So is your question about materials all answered-up now, Rich?

Actually you really need to tell us more. Do you just want to spin the motor, get RPM's for bragging rights or something, and not necessarily for higher HP? Need any torque along with the HP? They're all "streetable" to some degree, so drag race motor? Salt flats? Refreshed twice a month, or once a year? Daily driver? Money no object?

I think Pauter still makes aluminum needle bearing roller rockers, and you could probably even turn up a couple of their old race heads if you look a little. They're "streetable," but just barely, and depends on the street. If ceramics are out I think CB has an adapter sleeve to use lightweight T1 lifters in a T4 case. That or make the adapters yourself for the lighter lifters and cut to length aluminum alloy pushrods, Summit or Jegs. You'll probably want fuel injection, 24 flavors of that, depending on your wants and needs. I was at to the U.S. and World Touring Car Championship races at Sears Point last weekend and saw several cars using MegaSquirt, so no stigma there, no limits. CB ITB's for show or race, or one big TB for the street. You'd probably want a new forged crank sized for T1 H-beam rods, for the cost and weight, and probably LN's nikasil cylinders and pistons, but that depends on how much money you think all this is worth. And depending on your answer to that question about money or HP being more important, Len Hoffman's heads, springs, titanium retainers.

All that being said I've never built an engine like that, way too much for my budget. Choosing between all those headaches and the cubic bale of money or a radiator, I chose the radiator.

Ah, re-reading the question you only asked about the valve train, so forget the comments about crank and rods, throttle bodies and such.