I had some questions on piston tech and possibly a vacuum pump. It is time to go through our engine and was thinking of making some changes. Our current combo is 4.375 x 4.150 440 block. It makes north of 750hp. The compression ratio is 12-1. The pistons are SRP flat tops with 1/16-1/16-3/16 rings. I don't believe the block was ever honed with a deck plate. I am considering having it machined properly this time around and obviously new pistons.

So my question is how much difference in HP can thinner rings, gas ported pistons and or vacuum pump make? What is the maintenance schedule like on those type of parts? Do thinner rings need replaced more often? How often do vacuum pumps need attention? I will probably up the compression as well. How much compression can i run on 110 octane?

The car weighs 3460 with driver. Best 1/4 mile 9.67 137 mph. Best 1/8 6.09 @ 111. We shift at 6800rpm. For crankcase evacuation we have been using the tubes hooked to the headers. Currently that doesn't work for crap. I think we are getting a lot more blow by than we used to. I have not did any leakdown tests, because it is time to freshen it up anyways. This is my father in laws car. I just build it, but his first question is always "will it go faster".

My GZ pump has required no maintenance. The motor runs .9mm stainless rings. This is the 2nd time with these style rings. They were fine before it spun a bearing breaking a rod. Currently is coming up on 200 runs. Both times there has been no degrade in performance, oil usage, smoke, or blow by that I can tell. What are they worth performance wise? Hard to tell Its always had a vaccum pump, 10-12 in/hg. all things being the same I'd say maybe .05-.10 for the rings over the .043" that were there originally. Though the .043" ran pretty well. It has alway been honed with a plate. I should add it has verticlal gas ports as well.
Doug

I would give the folks at Total Seal a call, I think they could answer all your questions.

In my opinion the thinner the rings and the higher the vacuum the more horsepower you are going to see.

The surface finish on the cylinders is also very important. You need someone who has the equipment to be able to create the surface recommended by the ring manufacture and that means being able to measure it.

Smaller rings, gas ports and vacuum all will lead to more power. How much is based on the intended use of the engine and how far one takes it. On the heads up car we run .3 rings, obviously gas ports and as much vacuum as we can. But we have always done those things. The only change over the last few years has been going to smaller and smaller rings, which has led to more power and vacuum.

Thinner rings and a vacuum pump can add 50 hp to a race engine but the rest of the engine needs to be able to support another 50 hp. If you have good heads, the right cam, a good carb, etc. then sure, you should pickup some power.

If this is a dedicated race car then you might want to think about adding compression at the same time. For bracket racers I always recommend picking the CR according to the fuel that you can most easily find in your area. Usually 112 is available also everywhere so if that is the case for you then match your compression ratio to what works well with 112 and the engine should be happy for a long time.

We run alot of 1mm, 1mm, 2mm ring packs in our higher dollar high horse power application in hundreds of engines every year. (Not cheap by any means).
I still run old school 1/16, 1/16, 3/16 rings in my street / Strip 528 HEMI with a Moroso Enhanced Design 4 Vane vac pump with no issues with mine for several years now.

Run some 0.9mm rings and have at it. OEM stuff runs 1mm for 1000's of miles

Nowhere that I have lived or raced have I ever seen 112 available except at a track, or in pails/ drums from a fuel vendor.
On the other hand, 110 is readily available at the pump at a number of gas stations. Seen it available at the pump pretty commonly most everywhere.
112. Never.

Different states have different rules on uses of race fuel, the Street Outlaw show last night in Australia said that they weren't allow to bring in any leaded fuel and that it couldn't be bought down under either.
Probably due to them dang environmentalist activists

Thank for all your input guys!

110 is what we normally run. It is readily available at the pump in our area.

My father in law would really like to get into the 5's , but he ties my hands. I can't lighten the car at all. No rear gear change, no aftermarket block. We have been making north of 700 hp for 10 or 11 years on an oem block with no failures. I'm afraid that will change if i increase stroke or rpm range. So I am just trying to maximize what we got, within the rpm range we are currently running. I talked to him last night about a 4.5 bore block. He feels that he is too old to get his money's worth out of it.

Maybe also start looking at the rest of the car. Maximizing all the areas may help get him there as well. Trans gearing, converter, shocks, chassis set up, lots of ways you can lighten the car that do not change its appearance, titanium and aluminum fasteners for instance. Ceramic bearings can be used in many spots on the car to improve rolling resistance, as well as aftermarketbrakes that have less or no drag.

A vacuum pump and small ring pack will give you some power but its not going to be that significant. Combinng that will proper piston architecture, more compression is always a good way to make power. Combine that with a small ring pack and vaccum pump and it will ad up.

Agree with all this, that's where my mind was thinking anyway. Additionally "you're" asking a lot from a stock block and you should have him consider if the stocker breaks, how much is ANOTHER rebuild going to cost (TIME/money). Doesn't seem like there's a bunch of low-hanging fruit that won't add additional stress to the block BUT, give us a break-down of the total engine combo.

4.375 bore. 4.150 Eagle crank with chevy pin. Eagle rods. Srp flat top pistons, BCR caps and girdle system. Compression comes out to 12.2
The cam is a Jones solid roller. 268@ .050 intake. 276@ .050 exhaust. .465 lobe with 1.6 rockers. On a 112 lsa. IC is installed at 107
Victor max wedge heads with a ton of work in them. Super victor intake. 1050 dominator carb. I run 33 degrees timing with 110 fuel.
I don't disagree with the comments about stock block. I have been scared of it for awhile. I would have to add it all up, but I bet we have close to 1000 passes on this block.

The car is 3460 give or take a few pounds. Papaw has gained some weight lol. 4.10 gear 4500 stall. 28x10.5 Hoosiers. I worked on getting 60ft times down last year. Went from high 1.4's to low 1.3's. It made no difference in ET. The car mphs better with slower 60ft times. Double adjustable coilovers on front. Cal tracs with double adjustable on rear.

Get to the shop and tear it down before you make any decisions. If the block isn't cracked and the bearings all look good then I'd put a small dome on it to get the compression up to 13:1 or whatever the commonly available fuel at your track will handle. With new pistons I'd go with good rings but 4.375 isn't a super popular ring size so you kind of have to take what you can get.

Do you know what the actual stall speed is in the car? Launch stall and shift recovery stall? You usually need a data recorder or play back tach or something like that to know that number. If the stall speed going down the track is only 4500 then you could drop some time by going with a higher stall converter. With those heads and that camshaft you'll go faster if you can keep the engine in the 6000 to 7000 band all the way down the track. You are probably running 7300 or 7400 RPM at the stripe? I'm not sure where the peak power is with that combo but it could be right there in the low 7000 range.

Sounds to me like your having a fuel delivery issue in the last 300 ft of the track
I base that on past experiences with fuel delivery, every time we have picked up the 60 ft and 330 times the 1/8 ,1000 and 1/4 mile ET and MPH got better
after fixing the fuel systems
I say that based on the old theory of if you can't slow the MPH down by fattening up the mixture you don't have enough fuel delivery, especially in the 1/4 mile

I don't know the actual launch stall or shift recovery. I have considered putting a Go Pro in the car. In the 1/4 @7200 we were on the rev limiter. I had to set the rev limiter to 7400. He doesn't really run the 1/4 any more though. Transmission specialties built the convertor for the old combo that made a little less power. We sent them the dyno sheet of this combo and they said we didn't need a new stall. Although we really don't know where peak power is. We stopped at 6500 on the dyno every pull. I set his shift rpm at 6800. Depending on the track I set his launch at 3200 or 4000.
I am still working on him to build an aftermarket block.

You are probably spot on. We still run oem fuel tank. I know if we don't keep 10 gallons in it, the car acts up. A couple of years ago he went to a race without me and he came back and said there was something wrong with the suspension. He said it was wheel hopping real bad. I made some adjustments, and he went out the next weekend and had the same thing. This went on for a month and a half. I was pulling my hair out trying to figure it out. I couldn't be at the track with him that summer, because i was coaching youth sports. One day I pulled the car out of the trailer and it died. It was out of fuel. I asked him about it. He said "I put a gallon or 2 in it every so often. The gas gauge doesn't work." Long story short, he had been running it on empty all summer. The gas gauge does work. I put 10 gallons in it and we hit the track that weekend. No "wheel hopping" . It ran like a champ. I have convinced him to put a fuel cell in it this winter.

As I said before the overall picture is what makes or breaks a combo. Maximizing the power you do make rather than looking for more that you may or may not find. Converters are a make or break piece of the puzzle as is gearing and shocks.

Check with total seal on their ported rings. They have ports on the tops of the rings so you don't need to port the pistons, and they claim more even cylinder wear because the rings rotate so the extra pressure is not always at the same points.
A bit pricy at $623.62 set for 1/16"x1/16"x3/16" AP steel.
Moly are $369.92 SKU: CR9190GP 125


https://www.totalseal.com/rings/gas-ported-rings

One could go on forever to find that one extra horsepower or two. We even hot hone. We get the blocks up to operating temperature pumping hot coolant through the blocks while machining them.