1600 race engine questions--max rpm?

[alfabender]

I took my GTV race car with a freshly built engine to the AROSC time trial at Willow Springs this weekend and after a mostly good weekend the engine threw a rod toward the end of the final race. Here are some details and some questions:

- The engine had the following components:
Ported head
Weber 45s
10.5 mm "race" cams
Stock rods
Stock type pistons from a 1750 engine--makes the displacement something like 1650 and raises the compression a bit. I calculated the compression, taking into account head height, at around 10.5
All components balanced
Block was race prepped (cross drilled etc).
Spruell oil pan baffle

Note: This is the third engine I've run with this exact specification, in fact the same head and cams, but this time with a fresh valve job and carbs. I've run them to 8000 rpm before.

When I arrived at the track Saturday morning the engine only had tuneup time on it. So I took it easy, first going to 6000 rpm for a session, then 6500, then 7000, and finally during the race I bumped it up to 7500.

I checked the oil between sessions and it was so clean you could hardly see it on the dipstick, without any drop in level.

Also, the engine never came close to overheating.

What I noticed as I ran to higher revs was that the engine didn't seem as rev happy or strong at high revs, especially compared to the other 1600s I had before.

Finally, during the last race, the engine blew. Here's the sequence: I ran it to the rev limiter (7500 rpm) at two places on the track. I was racing closely with two competitors. On the 6th lap of the race I was running at 7500 down the front straight just before Turn 1, and as I came out of the turn I noticed a significant loss of power. The engine got weaker so I waved my competitors by and slowed down, hoping to get back to the pits. At Turn 8 I noticed a lot of smoke and bad smells and noises so I coasted back to the pits. When I got out of the car to inspect, and the smoke cleared, I found two holes in the block, one on either side, lined up with #2 piston.

Here's one theory of what happened: The engine was built with its tolerances too tight, which prevented high revving and robbed power. (Another theory is that the cross drilling was not done correctly--we'll learn that at teardown.) Either way, when I tried to run it to 7500 rpm it starved for oil in the #2 main bearing and spun the bearing, which later in the same lap seized and threw the rod.

Questions:

- What is the practical maximum for a 1600 race engine (I had thought 8000 or 8200 rpm).
- What does it take to run a 1600 engine at 8000 rpm?
- Does my theory sound right, or are there other theories of what happened?
- Is there any risk to an engine by running it up to the rev limiter--some shock due to the sudden loss of spark?

Actions I have are: (1) check the tachometer again to make sure it's correct--I can't do that till another engine is in the car, but I think I did that once or twice already and it was good to within 200 rpm, and (2) tear the engine down to see if there are any clues.

Doug Bender

[180OUT]

Doug, from your description it sounds like the power loss you experienced was from a rod bearing seziure. Although there are others here who know a lot more about this than I do, IMHO, 7500 is a bit much for stock rods under race conditions. If you can, you might take your motor apart and check the rod bearing clearances with plastigage. Carello rods or something similar would give you a rock solid bottom end if you want to turn 8000.

[Gordon Raymond]

Having spent over 40 years with various 1600's including GTA's, with some seriously altered heads and other variations, I've found not a lot is to be gained over 7500. The port and bowl design, even with 42 mm intake valves will limit power up high or useable torque down low. Stock rods carefully prepped will begin to stretch above 4000f/m. Modified pumps with straight cut, long gears can deliver pressure and, more important, oil volume, above 7500, but stock geared pumps, start to loose pressure and oil volume as slow as 7200, with a usual 3 lb. pressure loss by 7500, dropping quickly beyond that. Individual engines will vary, and much can be gained by reducing reciprocating mass.
My engine building is restoration of old race engines, with a close eye on preservation.
Jim's above suggestion is very real. Who can know what internal stresses have built up over time in 40+ year old Veloce rods? I use "I" beam Carello's, lightened JE pistons, with the light wrist pins, moly coated skirts, gapless rings in 79 mm. Yes, I have gone to 80 mm, but the paper thin liner skirts are a little spooky. For 80 mm pistons, block liner bores need to be opened up with custom liners. Valve gear is altered to use titanium valves, single plug @ about 41 mm intake. copper bryllium seats and guides, and titanium upper spring retainers. Followers are DLH treated. Blocks are drilled as 5 oilers, and 4 holes are also drilled in the upper water manifold directed at the liners. There are plenty of discussions on crank work here on the BB. Same for oil pumps. Pump pressure and volume must be there at maximum constant expected engine speed. Proper assembly and run in with performance engines is important, a well thought out 1600 can live a long time at 7000 to 7500 RPM.
There are many pure race engine builders here on the BB. Alfar7 will have (I expect) some critical ideas that differ from the above. Send him a PM, and he can tell you how to keep them alive at even higher speeds! Hope this helps. Gordon Raymond

[Alfapwr]

post deleted

[Subtle]

.....? ????? ?

[Alfar7]

Whats a good redline for a 1600 motor? Have you taken a look at the redline in a stock late 105 1600 GTV or Super? But what do they know right?
You take a bunch of 40 year old design parts, if not 40 year old parts and "balance" them and think 8000 rpm is reasonable. You deserved this break in your racing schedule!
If you want these motors to run over 7000 RPMs you need good quality race components. Lighter stronger rods and pistons. Note to you, the 1750`s pistons were heavier.
If the oiling was the problem the earlier track time would have been cut short.
When you first felt a drop in power you should have cut the motor & pulled over. You might have a motor now to rebuild.
Did you dyno the motor to see where your power band, fuel mixtures were?
Who built this motor? Did You?

[emr5503]

Here are the dyno figures for my 1600 GTA engine for the Bobsy I had built with Carillo rods, 2 ring Alfa slipper pistons, Shankle designed gearotor dry sump & Alfa 10.0 mm lift cams (can't remember the pn #).
Can't get the actual dyno #'s to upload, but happy to send them to someone who is more computer literate than I.
Would love to hear Richard's comments. The goal was an engine that would last a season & give me plenty of seat time, not a grenade.
Ed

[genericwood]

Doug, first of all, I'm sorry to hear about your problems! I know the sinking feeling when you realize the time and money required to build a new engine. And of course, it's even worse when it happens early in the race season.

A 1600 should be able to turn to 8000rpm. But as Richard pointed out, it needs Carillos and lighter pistons to do so reliably. In your post, you didn't mention what the oil pressure was immediately before your problem (or after)? I seriously doubt any problem was caused by the clearances being too tight. If they were, you probably couldn't get it to turn over when cold.

Depending on the rev limiter you are using, it shouldn't cause any stress on the motor. I use the MSD "soft touch" system in their 6AL system and don't hesitate at all to bang it off the limiter. For peace of mind, you may want to consider an ignition cut-out that is tied to your oil pressure. If you fail to check the pressures routinely in the heat of the battle, it will cut the ignition at a pre-determined pressure.

Erik

[Alfar7]

Ed,
The happy place with your motor even with your cams is under 7500RPM. Pityful admittedly, but to get HP numbers that you don`t have to mumble about under your breath you have to over rev the motor. Look where they are. Sorry.
I think you will find that your cam profiles are about those below adjusted for years of wear.
Cam Lift & Duration

Lift Max: .410 Duration (in degrees)
.001 360
.010 320
.020 290
.040 270
.050 260
.080 246
.100 234
.150 214
.200 188
.250 160
.300 132
.350 96
.400 34.410 Max lift
These are real typical of old design Alfa race cams copied by builders even today with just more lift and duration.
If I wanted replace the pityful I would address the ramp numbers that I highlighted in red to reduce overlap (and to increase length of the power stroke).
The durations in green represent the lifts over 50% of cam lift which is where mixture flow is obviously going to be best. This is a small port small valve motor, these numbers need to be improved.
If you are running the same cams intake and exhaust you are twice escrewed.
Compare the duration of the old Autodelta cams with the cams below that are in some GTA`s in Europe that are being driven to the track and winning!
These are not all out race cams. Thay make tons of torque in the small motors between 5000 -7000 RPM and pull from 3500 RPM resonably Look how close the duration numbers on the intake cam is fron .040 to .200. But the addtional .025 lift allows an tremendous increase in breathing from the point of real flow at .200 until the valve returns to slowing the flow. As well the assymetric application improves the combustion timing events to get the best torque production. Forget HP. Torque makes the car drivable. Torque wins races. These designs keeps your motor producing where it can live a long happy life. You can leave your wallet on it at night and know it will be there in the ayem!
Intake Exhaust
Lift .435 .435
.010 292 287
.020. 288 272
.040 267 260
.050 261 256
.100 234 228
.150 218 212
.200 189 182
.300 140 134
.400 72 68
.425 16 10
Max .435 Max .435

[Gordon Raymond]

Ed,
I like your post. It shows that my GTA engine and yours perform identically!
I have never seen this before. Ron Neal and I built mine in 1972 and ran it on the Prototype engineering brake. Though my graphed curves are slightly smoother, both torque and Hp #'s are nearly identical. We never ran mine over 7800 as the numbers clearly showed it was done.

I do need some info from Erik on the soft touch limiter. I contacted the manufacturer a couple of months ago and have pages of technical data sheets.
Are you using this with a stock unmodified Marelli S119A? How have you set it up?
Also, is it really SOFT enough for a GTA engine @ 7000, or does it terrify you and your driveline when it says enough? The unit in my 2002 BMW M3, shuts down that 6 very gradually, but that whole car is solid state, computer controlled, NOT mechanical in every sense like a 43 year old GTA!

Also, note that Richard has engineered me cams for both my single plug Ausca 1600, and the GTA engine. Study the numbers AND look at any old Alfa performance cam and you can visually see, on the cam, where Alfa was working by guess and by gosh. The reworked versions by WebCam are much superior.

[emr5503]

Richard.
Thanks for your input !!!
I'll be PMing you ( obviously need some of your cams ).

Gordon,
Points open at the same time.
My engine builder/original assembler of the car originally built an 1100 cc Alfa engine to run GM with a custom Moldex crank. He & Doc Wiley were friends. Turns out that Coventry Climax engines had the same bore as the 1300 Alfa, and they ran GM together. Then things changed and he went to 1300 cc and installed a GTA jr with his own designed/built Hillborn style F.I. system (CSR ?). Next owner blew that engine at the Atlan
ta runoffs and bought an AD/Shankle prepared 1300 cc engine. I blew that engine at Summit Point and decided to go 1600 cc because they always put me in with the Lotus 23's and GTA jr parts were getting harder to find. He has done a lot of dyno time on Alfa engines & has never been able to find any difference on the dyno with the 2 degree difference in timing for the distributor. All advance is in by 3500 RPM. In the future I plan to install a Jim Steck modified Datsun distributor, but don't want to disturb anything right now as it's "untouched" since coming off the dyno. I don't have any type of rev limiter, but should explore for the future.
Hope that answers some of your questions. PM me if you want to talk.
Don't think I'll ever beat the 23's, unless the race is long enough (when Charlie Gibson went by me coming out of turn 1, at SP, I thought I was backing up).
Ed

[Randy]

Hi just read about your engine blowing up, I just bought A bunch of Alfa parts from A guy and in the stuff is A completely rebuilt 1600 motor webbers and everything. It was built by Lee Midgley A pretty famous Alfa guy but I dont know what was done inside but I would sell it for 3000.00 call me if your interested. Thanks Randy 7602712508

[genericwood]

Gordon, I'm not sure what would be best for a twin-plug engine. But on my single-plug 2L, I'm simply running a Marelli Plex distributor off an 80's era Alfa. I use the magnetic signal from the Plex to drive the MSD 6AL ignition box that has the built-in limiter. You adjust the limiter with plug in modules. I don't worry much about the advance curve on the distributor, because the car is always over 5500 rpm on the track anyway. When the limiter kicks in, it feels like you developed a miss on one or two cylinders. It gets your attention, but doesn't give you a feeling of impending doom! On the 2L, I usually run a 7800 or 8000 module for races, but choose 7400 or 7600 in practice or enduros to keep my exhuberance under control!

I look forward to seeing you in Chicago. You will be at Autobahn, won't you?

Erik

Quote:

Originally Posted by Gordon Raymond I do need some info from Erik on the soft touch limiter. I contacted the manufacturer a couple of months ago and have pages of technical data sheets. Are you using this with a stock unmodified Marelli S119A? How have you set it up? Also, is it really SOFT enough for a GTA engine @ 7000, or does it terrify you and your driveline when it says enough?

[emr5503]

Pulled the cam cover and found out that the cams are pn# 10121032001 which are 10mm lift for 1300,1600,1750 & 2000 single plug Veloce engines according to the Performance Options Catalog. Seems the Autodelta GTA cams are 10.5mm lift. Can't wait to get a set of Richard's cams.
Ed

[Curtis]

Doug,

Very sorry to hear about your engine.

I am really surprised that you did not see a sudden rise in temperature in the minute before the rod seized. I have learned from experience that if an Alfa engine suddenly goes flat, or hesitates to pull, as you describe, that I should immediately back off and watch both the oil and water temp. A rod in the process of seizing generates a tremendous amount of heat.

Sounds like your main bearing spun and then starved the rod for oil? Was the accusump open? correctly plumbed?