Pointers on building a 16v race engine

[evanbottcher]

Hi folks,

I'm considering what it would take to build a solid 16v engine to drop into our Alfasud used in club sprints and track days. Currently I'm running a mildly warmed over 1.5L 8v - balanced, raised compression and a port job but standard valves and cams (the solid lobe type). I could invest further in this motor - cams would be a good start, but I'm wondering if a 16v would make more sense. I don't think there's a lot of knowledge here in Melbourne about how to improve the 16v however...

If anybody can share the basic parameters - how big you can oversize, what CR to run, what pistons and rods can be used, how big valves will fit, cams etc? Weak points that can be easily improved? Example is the hydraulic lifters - what's the readily available option to convert to solid type?

I want to build another engine that is reasonably reliable, no hand-grenade. I'd like to run the car on carbs - what size? 45s?

Any help would be greatly appreciated! BigSud? Sounds like there is a lot more knowledge in NZ...

thanks,
Evan.

[BigSud]

Howdy,

When I stuck a 16v in my sud, it was in response to all of the issues you'd raised with respect to hotting up the 1500 - and I was starting with a very solid 1700.

So, some questions if I may:
- Why do you want to hot up the 16v? It will be WAY faster than any 1500 right out of the box, mainly courtesy of having so much more torque.
- Why do you want to run it on carbs? If you get an old 16v 33 to dismantle (or a 145/6 if you're lucky - maybe you didn't get them during the hiatus?) then you just take everything you need and plug it in. The motor has it's own motronic loom, and connects to the car via two power wires. There's an easy 30 bhp!
- Given the above, why would you need to change the lifters? If you do that, you'll need 16 new ones, plus (very likely) 16 housing bores enlarged, plus new cams. Add that to the cost of the motor, and it's looking WAY expensive.

The next step for my standard motor (it has oilway mods, and has had the odd casting/machining flaw taken out of the ports) is to fit vernier pulleys, so that I can make sure the timing is absolutely spot on.

If anyone has the timing specs for standard cams (50 degrees BTDC @ .020" etc...) then I'd be very keen to have a copy!

After that, I'd be buying a Motec or similar mappable ECU and then remapping it to run on 98 (instead of the factory 91 map), and playing with advancing inlet cam timing etc, because it's a twincam motor and you can do it!

I'd reckon that 150 bhp should be on tap given all of that, with factory reliability and no more than 7200 rpm.

After that, take a look at AH Motorsports website - and see how much the next step costs - $$$$$$$$....

Chris

[evanbottcher]

Why would I want to hot up the 16V? You're right it might not be necessary to get a big power gain, but I'm definitely interested in what sort of mods are done especially in terms of valves and cams. Doesn't necessarily mean that I'd go down that path and spend lots of $$$ but I do like to know what my options are.

Carbs vs injection - the engine that I'm considering starting with is without it's injectors, motronic etc, so carbs may be a cheaper option than seeking another motor. I'll take this on board also and look at what my options are for getting a complete motor with injection and everything.

I had heard that the hydraulic lifters weren't real happy with sustained high rpms, and that replacing them with solid lifters was necessary for reliability. Not true?

A stock 16V is definitely an option - would be a lot less $$...

[BigSud]

It seems that the rule of thumb for hydraulic lifters is that 7500 rpm is the max they'll live with. Not sure why this is - too lazy to look, but I suspect it has something to do with fluid dynamics etc. Others will undoubtedly know more - care to enlighten us?

If you're starting without the electrobits, carbs might be cheaper to begin with. You might get away with 40s, but 45s would be a better bet. There's at least one nutcase in Europe running an overbored 16v on carbs - I think it uses 48s.

But the set-up cost would seem to be prohibitive to me, for dyno time, rejetting, recurving the ignition, etc etc.

I guess on balance there may actually be no overall cost difference between what I'm planning on doing (with the Motec etc) and your carb idea - but I have a reliable half-cost/halfway-finished option in the standard injection.

To each his own I suppose. One of my unexpected benefits of the standrd 16v is its total lack of temperament - you turn the key and it goes. Every time, hot or cold. And it drives smoothly, without fuss or backfires. Not so important for a track car I suppose, but having grown up with farty petulant carbs, it seems like Christmas every day I turn the key!

[87Sprint]

evan - surely having programable injection would be a huge advantage over carbs... to run carbs wouldnt you need some manifolds made up? if you stuck with injection and used a second hand computer im sure the cost wouldnt be much difference - you would need to dyno both setups... and as chris said you will have a much less tempremental and tuneable car..

the mechanic i go to here in adelaide has done allot of race boxer engines and ive seen him convert a few 1500 twin carbs to programable injection.. he might be a good person to chat too - pm if you want his contact details..

cheers -lucas

[BigSud]

Just had another thought - aimed at putting you off carbs...

Check out this guy's site. For some reason he junked the factory injection system, and look at the fun he's had...

http://www.alfasprint16v.fws1.com/

Chris

[joes33ti]

lucas which mechanic do you go to here in adelaide? i need my 33 carbs balanced!!

[87Sprint]

sent you a pm ..