914 DTM and Hybrid 2316, Both Dyno proven as of today Options

[Jake Raby]

19 Gallons of fuel, 24 full 2000-7500 RPM Dyno runs, Two FULL 12 hour days of trial, error, tuning and parts swapping- Its done!

Yesterday started out witha 140 HP first pull and disappointment- Today ended up with a whopping 40 HP tuned into the engine with no internal changes!!!!!

The DTM was really the easy part of this one! I knew from the minute it fired up and broke 200 degrees evenly on the quad CHT gauge that it was going to be a very easy task of perfecting the DTM for the 914. fact is we only had to make TWO small changes to the vanes to get the temps within 15 degrees of each other all around the engine! Plenum pressure differentials were less than 1PSI on both sides of the engine, and velcoity was within 3-4%! Pretty damn good for the first try with a slower than normal fan over drive (looking for power)

In cooling system runs we were seeing head temps with a 14 lb load at 4000 RPM of only 300 degrees! That was with a 180HP engine! The stock 100HP 2.0 runs FIFTY+ degrees hotter than that!!!!!!

As for the Hybrid engine and its power results- It kicked my ass. These heads, pistons, intakes and camshaft were all one off first time beasts. Due to this Brent and I fought for two full days with combinations of timing and jetting and even velocity stack and venturi sizes to find the perfect combo for the flattest torque curve, coolest temps and best EGT and BSFC numbers. Any time that we have a new combo with this many changes the dyno session is a huge learning curve when we are making the recipe's for all other "like" engines in the future that will follow in its foot steps- so what we do now is important for years to come, untio we supercede the combination.

This one was a pure bitch! Lens heads are so efficient that they did not like typical timing settings (only 24 degrees Vs 28-30 for a typical 2.0 head) and they didn't want very much jetting at all either, but they did like a gross amount of airflow.

This being the first engine of a new series- it did not meet my expectations of 190 HP. There are many reasons for this, the biggest being my camshaft choice. The cam I chose was NOT split duration. Len and I both felt that a straight pattern cam would benefit these heads- But we were wrong and the EGT I was monitoring was indicative of this in every dyno run we made. This engine did make exceptional HP as it is set up with LESS compression than the older "Annihilator" engine (9.5 now Vs 10.2:1 before) and a flatter more stable torque curve. The efficiency of this new engine is MUCH higher and it is running a gob more efficiently.

Basically the old engine made 1HP more but 7 lb/ft less torque with 15% less gross torque across the board! Len and I designed these heads to have exceptional velocity and not alot of gross CFM. This helps with efficiency, and pulling out of turns and overall throttle response. While the Dyno shows equal peak power I felt the difference in the controls and I have a good hunch that this puppy will be MUCH faster in the car than the old engine was.

This engine was the first for many new developments, coatings and tolerances. Below I will go over a few of them and what we found.

*I tried a new rod bearing for this engine. It is a NASCAR bearing that I narrowed myself to fit the Buick rod journal. This bearing coupled with my ION Nitrided crank and Pc-2 coating on the bearing made for a super low friction arrangement. This bearing and set up was set up with .001 less running clearance than normal- to a totally dangerous level- But it works exceptionally, even after 12 - 8,000 RPM full pulls!

* This engine received Full DLC coatings on all load bearing surfaces. (pushrod tips, rocker shafts, dizzy drive pinion, wrist pins, etc) These coatings reduce friction by up to 75% and the oil temps were indicative of this! I have never seen oil temps this coo, in an engine of this tune! I plan on ripping this engine down after the race season and checking for wear differences with the DLC coatings. We set our valve/stem clearance with DLC coated valves to ONE HALF of one thousandth- A scary level without DLC, but totally acceptable with it so far! This means less crankcase pressure past the guides, less guide wear and better valve stem support for higher revs with less spring tension

* Our new super light valve train with 7mm stems and a few parts that Len and I dreamed up worked exceptionally! With the ceramic lifters(58 Gr), Titanium pushrods, lightened stock rockers (lightened 15 gr) with lightened 911 adjusters(lightened 2 gr) and lightweight retainers we were able to retain valve control at sub 8300 RPM levels! This was achieved with only 230 pounds of OPEN spring tesnion and 120 closed tension! This is unheard of but severely impacted by the cam lobe characteristics, and dampening of the oddball valve springs! We now have a fool proof, easy to use and very cheap 7mm arrangement for high revving Street and Race engines! Time will tell more about its strength.

* We tried something new with Nickies and skirt clearance. To keep crankcase pressure down at high RPM and reduce blowby we ran only .001 of skirt clearance, thats a full .001 LESS than normal with Nickies! The engine has hardly any blowby- even when intentionally overheated.

* I also tried a total seal rings with Nikisil- Another risky situation as the support rail for the gapless ring is a chrome ring. Total seal said it wouldn't work, but Charles and I thought it would. After 24 full dyno runs the cranking compression and leak down is unbelievable! It seems to be working as oil consumption is non existant, and crankcase pressure is as well. It is much lower than we have ever noted with the conventional JE ring pack that we use with the Nickies. Total seal rings typically have severe issues with break in with a cast iron cylinder- These broke in with the Nickies on the first power pull! Its too early to see exactly what the outcome will be, but after a few Autocrosses, and Driver's ed events I'll know! We may have made a big risk here with some beneficial results!

* I gathered even more Velocity stack data and venturi data and their impacts on powerband with different tuning characteristics....... This engine didn't want a super short stack, but rather a factory Weber stack- Totally odd!

* Gathered data for the DTM venturi ring, and proved that it makes the cooling fan noise significantly less than without it installed.

So........What would I change in the combo if I did it again??? Well definately the cam! I'd use the same master grind, but add atleast 5 degrees of split to the exhaust side of the profile and possibly grind it on a 104 lobe center for a faster opening event to take even more advantage of these awesome heads! I plan on ripping it down for an inspection over next winter and I'll make those changes and redyno to see the differences.

I would rip it apart now, but I need to get this engine fitted into the car to finish the development of the 914 DTM and I also have to go spank some ass at the Southeast Dyno day on March 5th.....

The DTM and its internals are perfect, we will fit the engine into my 914 tomorrow, cut out the templates, scan them into autocad and get the waterjet on the ball with making them.

After Dyno Day I should have sufficient in car test results to support my dyno data to prove the DTM owrks. I will then rip this version of the shroud off then 914, make a mold for it and be fitting the next version with an oil cooler provision ASAP..... If that one works well on the first try like this one I should have TWO perfected 914 systems with molds made by mid summer!

Sorry for the long post- but it's 4Am and the mad scientist isn't tired yet! I'll post pics and graphs to my R&D portion of the site tomorrow.