Don Terrill’s Speed-Talk

This is a project I've been working on for a few months, on the final stretch now, it's a 2.3L L20B based engine for tarmack rally (road race on public roads closed for events).

I did the head for this a while back for another customer, it made 237hp @ 7200rpm on a fairly basic 2L short motor, we never got a chance to tweak it properly on the dyno as we ran out of time & had to get it in the car for a race meet - had some valve float issues (ran out of valve spring). Sorted the valve float but didn't get it back on the dyno.

The whole top end has now been sold to another customer (original owner has gone to the dark side with an SR20VE) & I'm building a 2.3L short motor to go under it.

New short motor has .160" (4mm) oversize bores, mainly to unshroud the valves as much as possible, but the extra capacity won't hurt anything either.
Block has a short grout fill to give the bores some more support.
Crank is from a Z22 - straight drop in into an L20B block.
Rods are Manley H beams for an RB30 Nissan - they share the same BE journal diameter but are a fair bit longer (6.05" compared to about 5.6"), they are also a fair bit narrower in the big end, so I'm running them as piston guided.
Pistons are custom made by SPS over here with a 1.2/1.2/2.5mm ring pack.

Some pics of the head back when I initially did the work on it, it has 45/38mm valves & a custom ground 261/264 @ .050" cam on 105 centres with .590/.570" lift.
It was originally an open chamber U67 casting, I welded up the chambers & started again:

New short motor:













I'll get some more pics up later as I finish getting it together.

A few other details on it - 13.2:1 comp, will run on E85.
Carbs are OER 48mm with 42mm chokes.

We have 2 sets of headers to try on the dyno, I'm pretty sure which set is going to be best, but they'll both get a run.

Boy that's Pretty
Racer Brown Would be envious

Love it! I am sure you have done airspeed measurements but by eye it looks like that low exhaust could use the floor welded up a half inch.

Love your work TK! If only I could afford for you to do me an L6 head!

I noticed you have moved the head over on the block too? Do you think this works better than angle milling?

Can't help but think it needs some more cam to take it to the SR20ve's!

Love it! I am sure you have done airspeed measurements but by eye it looks like that low exhaust could use the floor welded up a half inch.

A few guys have played with port tounges for the exhaust port floors, it does improve flow on the bench, but you can't raise the roof enough to get the appropriate CSA through the turn. It may show a couple of HP gain, but it's a lot of work for minimal gain, as it sits the head was capable of 2HP/Ci on a 2L short motor, so I'm gonna leave it be.

I noticed you have moved the head over on the block too? Do you think this works better than angle milling?

Can't help but think it needs some more cam to take it to the SR20ve's!

I'm putting the head back to stock location on this short motor - the larger bore unshrouds the valves enough that moving it over isn't required.
I'd love a bit more cam - hows about you design some lobes for me - a 266 intake with .620" lift & a 272 exhaust with .590" lift would be nice.
The cam in it has old Wade lobe profiles, ground by Clive cams, biggest lobes they got.

Could you use a KA24 bottom end under that head or are there class restrictions preventing you from doing so?

Beautiful work. The lit up shot with the manifold on makes me jealous, there's a severe port mismatch on my VW 8v manifold and they managed to put the mismatch in the manifold itself! 45mm necks down to about 32mm in a very ugly way to clear the mounting bosses.

It's for a 'historic' class, gotta be original type block & head, but internals are free.

KnightEngines wrote:

I'd love a bit more cam - hows about you design some lobes for me - a 266 intake with .620" lift & a 272 exhaust with .590" lift would be nice.

Deal! Will be another 2-3 months until my CNC cam grinder is up and running unfortunately though!

Let me know, this one could use more cam & I got another couple coming up.
Just final checked piston to valve clearance - I got enough room for more cam on this one no problem.

Pretty sure Stewart Wilkins would be very interested as well, if you're gonna do it maybe do lobes from 250 deg & up to mid 270's in 2 deg increments with the max intensity that'll fit on the rocker pads, I've still got a little room on the pads on this one, could be a little more agressive. Some dedicated exhaust lobes would also be nice.

Thanks TK, shouldn't be a problem - The joys of masterless! Will give you a bell when I am up and running.

What spring spec are you using for this?

I have NFI what the springs are! - 100lbs on the seat, checked open but can't remember.
Springs came with the head that this one replaced, I checked them & was happy, ran it at 90lbs on the seat before, just bumped it up with a little more shim - plenty of headroom in them.

Head after freshen:



Fitted up & checking cam timing:



Custom pan, holds about 9L & has 2x gates, baffles, crank scraper & a 1 way mesh windage tray:



Crank trigger:



Almost done: