Some tuning observations of "BIG" engines

[MASSIVE TYPE IV]

Recently we have been working with several very large displacement engines. In the past 7 weeks we have only built two 2270s, the rest have been 2,666,2615, 2680 and 2739cc engines(All Nickies equipped- of course).

I had grouped some of these engines together because they were all ordered around the same time and because I wanted to do a full batch of monsters for comparative purposes. I just finished the last one today- 2666 (80X103)

Seldom do we have so many "Super Heros" ready for testing back to back and I wanted to take advantage of the opportunity of like weather and play with the new data logger. Below I'll share some observations I have learned from these engines, each built for a different application, with a different overall goal- thats why some of the results are so interesting, because the traits seem to follow the engines(regardless of tune) much more than their smaller displacement counterparts, sometimes with the same camshafts.

Tuning: We have been finding that the tuning of the bigger engines, regardless of head work, chamber shape or camshaft/ CR is radically different than smaller 2270-2316cc engines. Most of the time with a 2270-2316 the engine responds drastically to tuning changes and you can easily pick up 10-15 HP just from timing adjustments alone during a run. This is just not true with the bigger engines. It seems tjhat once we attain the desired AFR that timing adjustments and "tweeking" just doesn't make as much of a difference.

This has been thecase regardless of CR or camshaft and also regardless of EFI or Carburetors as quite a few of my combos have been tested with each to expand my data based FI maps for later down the road.

I have one 2563cc combo that is basically a 2270 on steroids. It uses the same camshaft as a well known 2270 combo, same CR and even the same valve sizes in the heads, but the ports are afew ccs bigger and the chambers are as well. The last time I tested this combination it ended wanting a few degrees more timing than its smaller counterpart but put down basically the same BSFC numbers with about 15% more power through the curve. The odd thing about the engine was that it was so forgiving to tune- basically the timing could be varied by 6 degrees either way and EGT, CHT and power were not drastically effected like they were with the same combo on the 2270. This is undoubtedly related to the flame front and flame travel and the fact that the bigger bore allows so much more unshrouding than the smaller 96mm bore.

This really isn't bad at all, especially for the assembler/tuner because the engine is much more dialed in the first time it cranks up with even default settings. Sometimes it takes us all day to get a smaller engine optimized for CHT,EGT, BSFC and AFR for the best of all worlds- not true with the "Super Heros"... Yesterday the first run I put on one ended up being my final settings! I played with it all day today and didn't beat my first pull as the best overall power! BSFC numbers are showing ultra efficiency so we must be doing something right!

Power:
Through these tests I have seen some very odd traits with power, that I have never noted before. With the data logger I can watch much more of the engine and spend hours playing back data logs and comparing them. The odd thing is that the power of the big engines follows the camshaft much more than the cylinder heads, contrary to what we have thought before and proved with smaller engines. I had one engine with the same cam with 2mm less stroke and 1mm more bore and different head specs and the power band was still almost exacting (same exhaust, EFI AFR and etc). Yet again this proves the TIV engine is ULTRA sensitive to camshaft profile, even more so than cylinder heads!

EFI Vs carbs:
In the past few months we have been doing an absolute ton of EFI work. On one of the big engines I tried something very odd. I basically used a 48mm IDF carb to test the engine, then used the same carb as a throttle body with the injectors positioned in the manifold. So many times EFI Vs Carb tests are done with a throttle body change and as a result of the T/B being more efficient in its air delivery the engine produces more power, thus indicating that the EFI is making more power. Note that I'm not talkingg just peak numbers in this writing, but more importantly average HP/TQ numbers throughout the entire powerband.

My test omitted the T/B and utilized the carb as a source for metering the air. This created a constant that I really wanted to explore. The result was basically that the carbureted arrangement made better power by about 2% with the same given airflow on this big (2680cc) engine. The same test was tried last week with a smaller engine and the EFI set up made 20% more power than the same engine with same AFR with the same carb being used for fuel/air delivery!

What I'm getting at here is that the bigger engines have enough volume and velocity demand to increase the effeiciency of the Carburetor. The smaller engine benefits more from the FI because it lacks the "Double Vs" (Velocity and volume) at lower speeds to fully make use of the carburetor.

Running temparetures;
The big difference between the EFI Vs Carb tests on any engine so far has been the head and oil temperatures. I have datalogged every engine we have dynoed since I got the logger up and going and as a general rule head temps drop 30 degrees with the addition of FI to any engine, regardless to injector positioning with the same basic AFR as achieved with the carbs. EFI continues to blow me away with its power delivery and smoothness, I'm so glad we ave phased out carbs for our engines.

Now, the thing you won't believe is that run after run, test after test the larger engines, have ALL ran cooler temperatures on average (head and oil) than the smaller engines I build! This was regardless of EFI Vs carbs, even with some of the smaller engines also running Nickies, like the bigger engines always run. All the engines we compared were DTM equipped with the same drive ratios- Hell, today I had a very hard time getting one 2,666 engine over 300F on the head temps, even with full load at 5,000 RPM!!!!!!! Don't think that the smaller engines ran overheated, because the difference was only a few degrees, but was notable when compared with other tests in the same climate, with the same gear and same loads. So this further proves that bigger engines don't run hotter than smaller ones, even when the displacement delta is 500ccs++!!!! This is further backed up with my 275 degree head temps that I average on the 3 Liter all the time)

I plan on writing more on this subject later when I'll add a bit about direct fire ignition coupled with EFI in the conversation and why its such a huge benefit in my testing over and over again.

Match porting:
3 weeks ago I had a 2680cc engine on the dyno. Len wasn't done with the manifolds for it but I needed to get it fired up anyway. This engine has massively modified HAM heads and Len had a ton of work in the intake ports and match porting the manifolds.

So I ran the engine all day witharbs, got plenty of decent numbers but had done so only with a pair of off the shelf manifolds with NO match porting done. I was basically playing with the engine and getting it broken in for the EFI and correct manifolds to be added. I knew that when we added the right manifolds power would increase by at least 5% and it was already exceptional anyway.

So, we bolt the other manifolds on right after a power run and go back with it.... Power numbers didn't increase by 2%!!!! So I just knew when we did the same test with EFI that we'd see a big difference (it was my thought that we had maxxed out the carbs even with the smaller manifolds)

So we get the EFI all mapped with the honkin big manifolds and then swap them back out with the stock, non match ported manifolds- power difference was really non existant!

This was unbelievable to me and to Len and since I have been making sure to run this test on every engine I dyno, and we have been getting the same results over and over- that the match porting just isn't worth the work, even on a 2700cc engine! We want to back these numbers up with a stopwatch at the track in a road race car to see if the track gives us the same results- I believe it will.

Power:
I'll sum this novel up by saying that I have never been more hapy with the power we have been generating with the Super Hero engine program. Out of the past 7 engines we have tested, only one of them didn't break 200 lb/ft of torque, but it was very close (195) and all but two of them made over 200 HP. Each of these engines ran on pump gas and had between 9-10:1 static CR and a smooth powerband that simply did not need to go past 6,000 RPM for max power output! (Ultimate street cars!)

As we employ developments, continue to test and pay attention to the engine and what it wants it all becomes more clear that the sky is the limit with possibilities. We can never run enough tests, do enough comparison or try enough things to make the engine better. We are figuring out more infinite details of each engine, and always will be and due to that the engine program and knowledge base is growing by leaps and bounds.

Brent and I continue to learn, pay attention and refuse to be referred to as "Experts" ...... We have more fun every day, and thats all that counts.

So, I just thought I'd pass these observations on to you guys and let you know a bit of what I learned while I was "Off" the forums for 2 months. I have been so busy I just have not spent the time to make a post like this in a while, and for that I am sorry because I know those of you who find this as interesting as I do really appreciate these types of posts..

BTW-
I'm preparing for my next batch of Super Hero's now they include
69X105.7 "The Mighty Spyder" (2393cc)
82x98 For the last Meyers Manx to ever be built (2474cc)
82x102 for Cohibra's 71 Ghia (2680cc)
78x102 For an Outlaw 356 customer (2563cc)
84x102 Intercooled Turbo for a 912 Customer (2745cc)

I'll be datalogging each of these engines as well,and doing as many comparisons as possible- Speaking of that, i have one to balance as we speak! See ya!

[Wally]

First let me say: damn this is cool stuff!
Running temparetures;
The big difference between the EFI Vs Carb tests on any engine so far has been the head and oil temperatures. I have datalogged every engine we have dynoed since I got the logger up and going and as a general rule head temps drop 30 degrees with the addition of FI to any engine, ...

Amazing! Those observation are superinteresting of course, but how would one explain it?
Any theories? Better emulsification, thus more even burning (less lean hot spots in the combustion chamber?)?
Or just less specific Hp? (# hp/ltr)

Now, the thing you won't believe is that run after run, test after test the larger engines, have ALL ran cooler temperatures on average (head and oil) than the smaller engines I build!

Indeed amazing and defying logic (again )..
Any theories on this as to why?

Match porting:
So we get the EFI all mapped with the honkin big manifolds and then swap them back out with the stock, non match ported manifolds- power difference was really non existant!

Now this is scary!
Nice to know we don't need a ton of work on the match porting, but also frightening because it seems like we/you are stuck with the 200 hp mark because of this. Or do I get it the wrong way? If better flowing heads or more port velocity, or both doesn't bring more hp/torque, does that mean you hit a limit?
How do just plain larger heads (Welded heads with bigger valves, the old 48x40 combo with welded intakes) work in respect to your findings?

I know those of you who find this as interesting as I do really appreciate these types of posts..

I'll say!

84x102 Intercooled Turbo for a 912 Customer (2745cc)

That one will be fun to say the least but I thought you only turbo'd 90mm bore engines max...What changed your mind? (glad it did tho btw )

Thanks for this very interesting and fun to read post!
Look forward to a book of yours

Best regards,
Walter

[MASSIVE TYPE IV]

Wally,
Nothing changed my mind on the Turbo rule- It still stands.... At least with cast iron cylinders!

The cylinders on this engine are a project of mine and Charles from LN engineering- They will have encapsulated studs, basically a mimic of the Porsche RSR cylinder, but for a TIV. Charles has a customer with these running 2.5 BAR boost with great results! Thie bore size also allows the use of the RSR type sealing ring (NOT A GASKET) which is another addition.

As for the match porting thing- It further proves that the TIV isn't particular on the intake side of things, not at all. Thats why smaller carbs make bigger power- I made 200 pounds of torque today with a set of 45 dells with stock 38mm vents!

As for the cooler running temps- I believe its because the engines are generating less heat, or due to the serious unshrouding that Len has done to the heads that they are shedding heat out the exhaust much better than the smaller engines.

There are many more doors to be unlocked, some of it cannot ever be explained by a non engineer like myself- I just observe and figure out how to use it to my benefit!

[samcat]

Running temparetures;

~~~~~

Now, the thing you won't believe is that run after run, test after test the larger engines, have ALL ran cooler temperatures on average (head and oil) than the smaller engines I build! This was regardless of EFI Vs carbs, even with some of the smaller engines also running Nickies, like the bigger engines always run. All the engines we compared were DTM equipped with the same drive ratios- Hell, today I had a very hard time getting one 2,666 engine over 300F on the head temps, even with full load at 5,000 RPM!!!!!!!

Wow! Thanks for sharing all the Jake. Will need several readings to really absorb it all.

Does the above (quoted) go partway to explain why some of the european tuners running BIG engines with porsche cooling dont experience some of the problems that you would expect?

Again, thanks for sharing.

Sam C

[Stripped66]

Jake,

do you think the observations in the temps running cooler in the larger engines are more due to the larger bore and increased surface area of the cylinders (both inside and outside) than displacement? If so, I would imagine that your upcoming 69x105.7 build will run cooler than a comparable 96mm piston'd stroker, despite having similar displacements.

[Cohibra45]

Jake,

I am getting more excited everyday. I was just thinking that the reduction in temps may be due to the coatings used. Ron (Plastermaster) told me in one of his posts that he observed opening his hood after a 30 minute run, how cool the engine compartment was. He said his exhaust header was comparatively hotter.

Man, I can't wait !!!

Kelly (Cohibra)

[raygreenwood]

Jake....what you are seeing in match porting not being important...may be misleading you in the long run. Some things to think about.

Generally, from my experience...match porting doesn't change things much on EFI......UNLESS....the location of the joint between manifold and head is in a location with reference to the injector...wherein the turbulence it creates.......causes very very bad spray pattern changes.

It takes a pretty big "bump" to mess up the spray pattern of stock type 4 manifolds because of where the injectors are located....with reference to the bend at the bottom of the runner..... right before it connects to the head.
Now...when you start moving the injector.....too far upward on the runner....it begins acting mroe like a carb. As long as you don't get fuel fallout or condensation...it should actually help to have turbulence at the joint from no match porting. So as you note...possibly no difference.

BUT....putting the injector on the inside bend of the runner...may cause some of the worse problems. The injector spray is then not spraying into the most dense part of the airflow column....which "flings" the air mass to the outside of the bend radius due to centrepidal force.

One thing though.....I have found that if the match porting is poor enough...such as when you use 2.0 914 runners on 1.7 heads....that can be a problem...BUT...ONLY on small engines. The smaller the engine (as it appears you are finding)....the more that really subtle changes affect the tunability.

On a tightly tunned 1.7....little things like polishing the inside of runners, fuel stability to 1/2 psi, minor volumetric changes to manifolds, balance of injectors, careful smoothing of port areas in head...etc.....make a real difference in throttle reponse, power and tunability.

What you really need to do is cast a see through runner, or at the very least....be able to film inside the runner.

Though match porting on small engines like the 1.7 will not make you any power (as you have found)....they can greatly affect drivability at certain rpm transitions. Just some thoughts.Ray

[Santas Brother]

On the flow bench,I have observed definate increases
in flow from a deliberate mismatch between the port
and manifold,usually on the short side.

Unfortunately,I havn't proven this on a dyno.

Of course,it depends on where the mismatch is and how much.
The same amount of mismatch in a different spot,might make no difference to flow,or could cost flow.

[MASSIVE TYPE IV]

Len has seen the same differences on the flow bench, even with the same engine that we were playing with..

These findings are VERY odd an I definately plan on backing them up test after test before I make a "Ruling" on the impacts..... Like I said, we want to back it up on a stopwatch, because the dyno is steady state and not accelerating so results may vary in the car.

Just as an observation to ponder- thats all!

[raygreenwood]

I guess its really a matter of how we ask ourselves the "questions"....before we start experimenting.

With intake manifold work....most people are concerned that what they do may either increase or decrease either flow (total airflow volume) or velocity.

In the case of match porting on small engines (or even large I guess)....its one thing to ask...."has this affected flow or volume"....and quite another to ask...."does this affect atomization and proper mixture".

You may do something that has little or no affect on volume or velocity....but in just the right situation it can affect what the injector does. It may even....affect the metering if it influence vacuum or harmonics in the manifold.

As Santa brother noted ( and I'm not sure if he meant better flow volume, velocity or just better HP on the dyno )....you may even see no change to airflow volume or velocity...but create just the right turbulence for better charge filling of the cylinder or better running through better homogenization/mixing of the mixture in the port.

One partial problem with the stock injector location on type 4's....was that with the incomin air sweeping around that bend....it does tend to sweep injected fuel forwardx toward the valve....but also sweeps it downward against the port wall. You can see this pattern in engines that ran rich for a long time......as a clean "swath" on the floor of the port in the head going up to about 9 and 3 oclock rescpectively...and tapering off. The rest of the port that never gets contact is baked black with fuel residue.

Perhaps...a ledge above that area may create a downward scooping affect. Something to ponder.Ray

[Santas Brother]

We were experimenting at the time with twin cam Alfa Romeo heads
for SCCA GT racing.

Managed to get what was supposed to be a "good" cylinder head,
already ported.to use a our base line.
Looked like all they did was make the ports bigger all the way around.
The stock,VERY POOR inside radius,only got worse.

Adding a buch of material to the port floor increased flow signifigantly,
as did making a step on the floor where the manifold met the head.

We didn't have any way of measuring velocity at the time,but would
like to add that to our new flow bench,which should be finished in a
few months.

[Plastermaster]

Thanks for sharing all that. That would have taken me all day to type!
The carb EFI comparison is interesting to me. I am thinking that carbs could be improved upon for our application. The Webers and Dells were really not made for our engines. They were adapted. For street cars more and more people are rethinking carb sizing, in favor of smaller is better, but at a cirtain point flow becomes just too restricted. Same with heads, as we have fouind the importance of the finer aspects of head work over total flow #s. I am thinking the best carb set ups are where the TB is as small as will flow sufficiently and the vent as large as the engine will handle.

Ron

[HAM Inc]

I'm still digesting Jakes findings with regard to limited power increase with the port matched intake. A couple of ideas jump right out. First though let me say that the heads picked up about 5% more peak flow on the bench with the port matched intakes over the unported manifolds. Doesn't sound like a lot, but in terms of a bolt-on increase it's big.

My first inclination was that the increased velocity of the mixture at the point of entry into the heads with the unaltered manifolds compensated for the loss of flow.
Jake also pointed out that the smaller manifold might have an anti-reversion effect, which is known to be helpful with intake and ex. systems. I can't address the latter as the experiments I'm aware of with intake anti-reversion systems were more sophisticated than just a lip working against reverse flow. But who knows? Maybe that's all it takes
As for the former I can definitly see the potential for increased velocity at the head entry being beneficial to mixture quality to the point that it trumps the increase in flow.

My other thought was that the extra flow from the port matched manifolds might require an adjustment in cam specs.

The reality is that Jakes new findings have sparked a new tangent direction in R&D. It will take a lot of experimentation on both of our parts to sort out and triangulate his findings.
In the short term I am comfortable in advising my customers to save their money and not bother with port matching for a typical street engine combo. However, it is a good idea to make sure that their is no serious misalignment that puts a significant sharp edge in the flow path.

[MASSIVE TYPE IV]

Excellent post, Len.

Your mention of the camshaft profile is interesting, because I had the same thought pop into my head last night. We have already proven that the engine definately loves split duration, with more suration on the exhaust side of things so perhaps the manifolds are enhancing that effect further????

[Justhebegining]

I just want to know one thing...

I bet waiting for the next work day is like a child on Christmas Eve waiting for Christmas! lol

Keep up the good work...now I understand!