4.1 Birth

[Pablo]

What I'm trying to ask is that say you have a small turbo at 25psi running a certain ET and it takes 20psi to run the same ET on a larger turbo. The 20 psi I would think would be easier on the deck of these engines were they are prone to crack. Just my thoughts.

Thats only because the larger turbo in your example is more efficient than the smaller turbo. They are producing the same volume of oxygen, one just needs more psi to compensate for the heat it is imparting on the air which makes the air less dense. It also makes air molecules spread out which is why you can see more boost with the same amount of air if it is heated. Like a nitrous tank, if you heat it, pressure will rise even though the amount of nitrous in the tank didn't change.
If they (small turbo/big turbo combos) run the same times they are generating similar cylinder pressure during combustion.
The danger to the engine in running the smaller turbo lies in the heat it is imparting on the inlet air. This will make the engine more detonation prone and that is what breaks things.

 

[tom j]

Thats what I wondering, if cylinder pressure would be much different

 

[boostingbuick]

Ok Tom, I went and did it. I have a Turbonectics DBB 72 S trim with the new F1 wheels. So now you won't feel like such a ginny pig. So do you have any updates or new pics?

 

[tom j]

I have done some mocking up with the gt42, I have some minor fab work to do just waiting for the holiday hangover to subside. I also plan on running a second fuel pump due to the extra needed for E85. Are you going to the Nationals this May if so we are going to have to get together

 

[boostingbuick]

I would love to go this year. I have not planned that far ahead this year. But if I go I will let you know. Would like to sit and chat with you, but your also counting on the fact that both of our cars will still be running.:redface: . I had no plans for this but my Bro is steping up his set up looking to beat up on me a litte. I will have none of that. I don't like it when I build a car that is faster than mine. Or at least another buick. I plan on sticking to pump gas. I was hoping for 10.40's or so.

The updated pics are great. Keep them coming. I will need to post some pics when my parts start getting in.

 

[tom j]

What are using for tuning? WB, T-pro, translator ect...

 

[STP]

Years ago a friend of mine, Dwayne Thompson, went 10's with the 4.1 before it split the cylinder wall.. Iron headed...70 turbo and hyd roller..I think it was hardblock'd to the freeze plugs, but don't really remember. Interesting project. Would love to see one hold up in the tens...

 

[boostingbuick]

I am using Bob's chip. Good luck so far, and the tune has been on the spot. I am going to see how far it will go.

I need to figure out how to do quotes.


STP,
Tom and I have been to the Tens with ours several times. So I think its safe to say they will live in the tens. And what was done to the bottom of your friends motor? If it did not have caps or a girdle then I can see why it did not live. Most 109's won't either with out some help.

 

[STP]

Don't really remember what was done to the bottom end..But that had nothing to do with the crack in the cylinder wall. The car still ran ok, but was pressurizing the coolant tank. I'll try to get him to post...I wanna say he ran a 10.68 with it before it came apart, but don't hold me to it.

 

[Dwayne]

Scot, you are correct, it did split the cylinder wall in a couple of places. The block did have steel caps. As I look back on it, at the time I was using a RA chip with 72# injs and NO maf. At that time, Red could supposedly burn a chip that would idle and run without the maf. Never did work right and always had detonation, wether it be at idle or wot. Everything changed when I went to a ME-R, car idled and ran great but the damage had already been done. I believe that today you can/could get one to live in the high tens with todays technology and meth injection........my only concerns would be the thin deck and cylinder walls in an all out race app.....you might get one quicker, but I think you would be living on borrowed time............on a side note, did you ever sell your black car ? We could still slap a number on the side of that bitch and enter it in the figure 8's at Anderson Speedway.....hell, I'll drive ! :biggrin:

 

[boostingbuick]

What bore was it? I know I am running a big piston at 4.030.

 

[Dwayne]

If I remember correctly, it was .020 over with hyperutectic pistons ( which I would never do again) they crack way too easy. I would'nt hesitate to build a 4.1 for a street motor, but I wouldn't wanna log too many passes on one. Unless somebody was behind me with a shovel......:biggrin:

 

[tom j]

How many people have actually broken there 4.1 prod. There are alot of negative things said about them. Maybe some other people will chime in that have 1st hand experience with cracking the block/deck ect...
I know there are plenty 3.8 broken out there, but how many 4.1?
MAYBE A SURVEY

 

[boostingbuick]

Ok. But I agree, just because one person has had an issue does not mean that all of will. Plus it was induced with detonation.

 

[STP]

There aren't as many blown up 4.1's as 3.8's due to the fact that few build them...I hope it works out. Fun project, quite a few folks have built the 4.1's and gone back to the 109 for whatever reason. However, nowadays it may be possible to make one live...Just don't want to give new Buick readers/owners false hope and think that the 4.1 is most reliable way to make power.

Dwayne, still have the Stage 2 car...It can sit here for all I care, until I decide to go racing again. Hard to justify it right now....But that could change any day : )

 

[boostingbuick]

And I don't want people making noise about a 4.1 being weak. Unless you have some proof about them being weaker. At the same time I don't want there to be a black cloud over a 4.1. And the worst part is that most of the people building a engine will never make more than 500hp. So even if the 4.1 is weaker ( that has not been proven to me) the people would gain from the extra c.i. and not break it. But as far as a race piece, they are all on borrowed time. Thats way they make stage 2 stuff.

 

[STP]

Chris, sorry for the hijack and good luck with your project.

 

[tom j]

There aren't as many blown up 4.1's as 3.8's due to the fact that few build them...I hope it works out. Fun project, quite a few folks have built the 4.1's and gone back to the 109 for whatever reason. However, nowadays it may be possible to make one live...Just don't want to give new Buick readers/owners false hope and think that the 4.1 is most reliable way to make power.

Dwayne, still have the Stage 2 car...It can sit here for all I care, until I decide to go racing again. Hard to justify it right now....But that could change any day : )

Maybe these people that had 4.1 and went back to the 3.8 will speak up on there experiences bad/good

 

[ChrisCairns]

Chris, sorry for the hijack and good luck with your project.

I don't think it was a hijack ... all these posts are interesting with good information regarding the 4.1.

 

[boostingbuick]

Thank you for understanding. I would like to hear my info from anyone with some experience with these things. Plus any new pics Chris or Tom? I have not gotten my turbo yet.