TR2/3/3A TR3 the neverending search for more torque and HP

[newguy]

I am tearing down my 1931cc engine and going for a major increase in TQ and HP. One of the major items which I am hearing about from a number of racing engine builders is a small port head that I believe came off the early TR4 motors. It has 1 3/8inch ports instead of the 1 5/8inch ports on the standard TR3 heads. If anybody can assist me with info on this head including the availability of a good head, please respond.

 

[martx-5]

I'm assuming that you meant 1991cc engine, as unless the liners have been changed to a larger then 83mm bore, that is what came with the TR3s.

I'm not sure which head is the <span style="font-style: italic">best </span>on the TRactor motors, but I seem to recall that the last rendition of the TR4A had the largest valves and best flow characteristics. But, that alone will not bump up the power a whole lot. What will is a ton of money... :laugh:

First you have to define how much power you are looking for, and where the car will be used. Building an engine for the track is very different then building an engine that you can live with on the street.

I drive mine on the street and did some mild work on my TR3 engine that I am quite pleased with. I went with 87mm pistons & liners, milled the head about 0.080" for a boost in compression, had the cam reground for more duration and lift, and put on a tubular header. According to a very reliable source (Ken Gillanders at British Frame & Engine ) , this most likely pushed the HP from 100 to about 120-125...a nice jump. BTW, I got most of my parts from Ken. He really knows his stuff when it comes to modifying these engines. It might be worth calling him and discussing what you would like to do. He's a wealth of information, loves to talk, and has a lot of the parts you may be looking for.

 

[Tinkerman]

I second Art's suggestion. He helped out a bunch when I was rebuilding my engine.

Tinkerman

 

[TR3driver]

3rd on BFE.

The "small port" head was for late TR4A; basically the same casting but the earlier heads had the first 1/4" or so of the port opened up to ensure it didn't protrude into the manifold port. These heads also had the smaller 5/16" exhaust stems. See https://www.tjwakeman.net/TR/FAQ_heads.htm for more details. Don't know how available they are in general, mine isn't for sale.

You might also want to talk to Larry Young ( Tilden Technologies ) about his new street cam. I've got mine, but haven't built a motor for it yet.

A better exhaust will help a lot too, but the various tubular headers don't last as well (and radiate more heat) than the original cast iron lump. They also don't usually fit with the early starter, so if your car is before TS50k, that might be a problem.

 

[newguy]

Thanks for the info. As always, this forum is a wealth of knoledge and support.