Which way to go ...109 stroker or 4.1 ??

[TexasT]

One other point--have you guys ever noticed that a new engine always seems to run better after 5k miles or more?

Don't tell the top fuel guys that. They never see that many miles on their builds.
I would think it would depend on how tight you set the build up. As things get "broken in" and 'seated' things just work better. If rings don't seat or pistons are tight or loose, the engine isn't going to make optimum power. Just like if the crank is loose or tight it just isn't going to "go long".

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[TTipe]

Great info. I haven't assembled one yet. Though I do have a block that passed a magnaflux by my machinist. I understand the limits. I understand the thinner deck and cylinder walls. I also understand that 5k miles of weekend racing/cruising might be over a decade of time. Using a forged crank and main caps to try and control the flex and thus control or at least put off busting out the webs for a while. Then maybe move over to a ta block. But at that $, I'll stick with production stuff I find in the wrecking yards and Craig's list for the budget I work with. Just the pistons equal what I spent on the block, crank, machine work, cam bearings and gasket set.
I am glad you are adding to the mix, lots of good info you provide. No replacement for displacement, or we would all be hunting 3300 blocks and going for longevity.


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The way to go fast on the cheap with some longevity is the use of 3800 series 2/3 blocks. There are some quick cars out there running on center low deck blocks.

 

[Jay J]

Agreed. that is why I asked you about your testing results on the 3800 Blocks. The cheap factor diminishes when you have to fab up mounts, headers, etc. Other threads cover this in detail; including multiple requests for a kit to become available for those of us without the skills/equipment to make that swap.

 

[Nick Micale]

Nick I tend to disagree from a longevity aspect. Race engines are continuously "freshened" so perhaps longevity is not an issue. ............

Well, this is a first, I have had others disagree with me before, but never 3 times in one thread!

I respect your information, but since all blocks are not equal in strength and durability, we cannot say or predict how long or short the life of any production block will be?

Years ago it was unthinkable that a 109 block would even get into the 9's, much less live there for a while.

Fortunately, I have not yet found the limit of the 4.1 blocks for any of my personal engines, or my customers?

I have built and used many 4.1's and currently have 2 in use, one in the race car, the other in a street car at 500+ and 600+ RWHP respectively.

The race car has 5 or 6 track visits with high 9, lows 10's in this evaluation period with no issues so far.

My opinion on the deck strength is that since the TA alum heads are much stronger and rigid than iron heads, deflection is a lot less.

I do not have a lab at my disposal, so I resort to real-world experience, and what we learn from our mistakes and mis-haps.

What we have learned from experience with the 109 blocks is that the weak "link" is the web between the cam and crank bore, and have seen many of them crack there. I am less concerned with the head surface than the web giving up first on a 4.1 block as well.

In a couple weeks I plan to pull the irons heads off my street 4.1 to examine the head gaskets to see how well they have been sealing, and will also check for any block cracks around the studs.

A this point, I do not know the limits of a 4.1 block, but we WILL continue until we do know where and what.

I do think we can reach the same level of performance and reliability with a 4.1 and as 3.8, but time will tell as we continue to push the envelope!

 

[TTipe]

Well, this is a first, I have had others disagree with me before, but never 3 times in one thread!

I respect your information, but since all blocks are not equal in strength and durability, we cannot say or predict how long or short the life of any production block will be?

Years ago it was unthinkable that a 109 block would even get into the 9's, much less live there for a while.

Fortunately, I have not yet found the limit of the 4.1 blocks for any of my personal engines, or my customers?

I have built and used many 4.1's and currently have 2 in use, one in the race car, the other in a street car at 500+ and 600+ RWHP respectively.

The race car has 5 or 6 track visits with high 9, lows 10's in this evaluation period with no issues so far.

My opinion on the deck strength is that since the TA alum heads are much stronger and rigid than iron heads, deflection is a lot less.

I do not have a lab at my disposal, so I resort to real-world experience, and what we learn from our mistakes and mis-haps.

What we have learned from experience with the 109 blocks is that the weak "link" is the web between the cam and crank bore, and have seen many of them crack there. I am less concerned with the head surface than the web giving up first on a 4.1 block as well.

In a couple weeks I plan to pull the irons heads off my street 4.1 to examine the head gaskets to see how well they have been sealing, and will also check for any block cracks around the studs.

A this point, I do not know the limits of a 4.1 block, but we WILL continue until we do know where and what.

I do think we can reach the same level of performance and reliability with a 4.1 and as 3.8, but time will tell as we continue to push the envelope!

 

[TTipe]

Nick I merely said that the 4.1L can't seal up for a reasonable amount of time given the typical usage (a few weekend strip trips and mostly street racing/cruising) based on the user community. The distance from the bore wall to the bolt centerline may float 0.005 on a virgin block straight out of Factory 36 (flint Michigan). I don't know of many folks that are not reducing that distance by boring, honing and or fuzzing bore walls. As the bore wall gets closer to the head stud centerline the ability for the stud to tug the bore wall out of shape increases. We still have the siamesed bores pushing on each more now that the bore walls are thinner. Also since we probably double to triple the energy released in the freshened cylinder bore ( in the form of chamber pressure and heat) the bores will become more unstable. You are correct that not all 4.1L blocks are the same. You have the results from production variability (who has a stable 4.1l untouched block "291" from an 83 Park Avenue?) which probably won't seal over the long hall along with "0.020" and "0.030" cleaned up bores which are "further weakened". Have you ever seen cracked 4.1L decks from the head studs which were not countersunk? We both have and this is indicative of what is going on. This is the tell tale from chamber pressure and the mechanical forces involved in the combustion process. Even though we countersink the stud holes to eliminate the deck "stress riser", the forces are still the same. Buick Engineering never saw fit to countersink the head bolt holes in production at the production power levels. Older 4.1L blocks would show "hair line" cracks in a few instances. Multiple 4.1L blocks were reviewed for cylindricity having been sampled from the engine plant and dyno durability runs at production power levels. Again they were the worst clover shaped bores of any of the Flint displacements when reviewed on the talley round. Nick to say all blocks have a "unique" character can be true do to casting core shift but I have never seen any Buick pace cars (Indy, Unocal , etc) running other than stage blocks until the early 2000's. Stage blocks were plentiful & confidence was high in the early days. The rules did not prohibit the use of (sportsman) blocks. Later on production engines were required (Turbo TA). The Corvette Yellow Monte Carlo's (with "Taz" on them) that paced Nascar used stock 3800's which were supercharged and had to meet Nascar's acceleration and durability requirements.(The 3800's displayed phenominal durability given their regular duty with the Pittsburgh and San Diego taxi fleets. The Vehicles were returned to Buick engineering with well over 200k miles and still running fine. They were still getting great mileage, the bores must be sealed up.) I know because the Bristol / Charlotte Motor Speedway cars were my responsibility. A vehicle motor division does not take large risks in the public eye (that's why stage motors in pace cars were the obvious choice). The very first 4.1L turbo regals were built in the late eighties/ early nineties by Dennis Abbey out of Quality Engineering in Fenton Michigan (he lived down the street from me) and yes they used stage blocks (Quality had the inside track on the production 4.1L blocks) . The Grand National/T Type Chief Engineer Tom Wallace (may still be vehicle line exec for Corvette) used a stock Turbo 3.8L engine in his white Grand National "Tommy's Toy". Tom was a racer and probably would have preferred to go with a stage block, but had confidence in the turbo casting at the power level he was running or a stage block. I hope this endeavor works well for those who undertake.

 

[dynoman]

Sooooooo... to come back from that hard left turn this thread has taken. A stroked 109 would be a better choice from a durability stand point , and with the same mods, ABOUT the same power ?

 

[TTipe]

ry

Sooooooo... to come back from that hard left turn this thread has taken. A stroked 109 would be a better choice from a durability stand point , and with the same mods, ABOUT the same power ?

I have only described on this board what I dealt with as hard data (without the numbers but with the visual logarithmic results) along with experiences and tutilage from the people that I worked with who released the turbo v6. I make decisions/comments based strictly on the data not my ego/emotions. Personally following the 4.1L production block path does not work for me / my goals. My comments were not meant as an assault on Nick or anyone else. Nick is a very knowledgeable racer/engine builder and has seen much more than I have for sure. I know this first hand.

 

[Jay J]

I, for one, am thoroughly enjoying TTipes history lesson. Thanks for taking the time to post it!

 

[turbobob924]

Watching

 

[gtfrede]

Love the info in this thread! I dont care about u turns left turns right turns etc if its awesome info that would otherwise not be exposed....

To input on the original question I would personally go with the 4.1 stroker...cubes cubes cubes

 

[goche4]

I'm happy with my 109 block if I were to redo I would stage block

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[MCH86GN]

Agreed. that is why I asked you about your testing results on the 3800 Blocks. The cheap factor diminishes when you have to fab up mounts, headers, etc. Other threads cover this in detail; including multiple requests for a kit to become available for those of us without the skills/equipment to make that swap.

Too bad there isn't aftermarket support for the 3800 series, with respect to rotating assemblies, etc. Although there still seem to be enough 109's to go around, it would be nice to be able to build up a series 2/3 3800.