Broken timing chain...
#47
02-28-2011, 07:29 AM
Join Date: Mar 2009
Location: Northern Virginia
Posts: 334
Rep Power: 48 
#48
02-28-2011, 07:45 AM
This is very interesting! I've never thought about the air movement being a problem inside the block!!
#49
02-28-2011, 07:57 AM
Registered User
Join Date: Aug 2009
Location: Houston Tx
Age: 39
Posts: 2,496
Rep Power: 186
The air cooled guys have said they have seen gains upwards if 40hp making the windage of the flat block improved. It's similar concept with knife edging a crank.
Round and smooth all transistions that would catch air. So there is less drag when you push n pull air from one cavity.
Round and smooth all transistions that would catch air. So there is less drag when you push n pull air from one cavity.
#50
02-28-2011, 11:39 AM
Justin,
The luck we have had with our cars... urrggg!!
That said though, bigger and better to come and I'm sure the outcome will be worth it after it is all over and done with.
I have went without any accidents until my third 996TT which is pristine and I manage to hit a deer and then some black ice allows me to say a very close hello to a guard rail. Glad the damage was minimal but still... you can make this crap up!
Cheers,
Allen
The luck we have had with our cars... urrggg!!
That said though, bigger and better to come and I'm sure the outcome will be worth it after it is all over and done with.
I have went without any accidents until my third 996TT which is pristine and I manage to hit a deer and then some black ice allows me to say a very close hello to a guard rail. Glad the damage was minimal but still... you can make this crap up!
Cheers,
Allen
Last edited by Almo; 02-28-2011 at 11:49 AM.
#51
04-02-2011, 12:27 PM
Join Date: Mar 2009
Location: Northern Virginia
Posts: 334
Rep Power: 48
Starting to get all my stuff in order for this engine rebuild and car overhaul... 
In this pic:
In this pic:
- USP hard pipe kit
- 997.2 intercoolers
- Samco hose kit
- Forge DV's
- 911tuning.com 3" custom sport exhaust
- H&R sport springs
- GMG front and rear sway bars +adj toe links - not shown
- Raceware 10mm headstuds
- Pauter rods
Last edited by atisvt99; 04-12-2011 at 09:17 AM.
#53
04-02-2011, 02:46 PM
The air cooled guys have said they have seen gains upwards if 40hp making the windage of the flat block improved. It's similar concept with knife edging a crank.
Round and smooth all transistions that would catch air. So there is less drag when you push n pull air from one cavity.
Round and smooth all transistions that would catch air. So there is less drag when you push n pull air from one cavity.
I have a hard time believing 40hp with air movement. Oil drag maybe, but air does not have anywhere near the same coefficient of friction.
#54
04-02-2011, 05:53 PM
In response to the previous guys question, the only way I can figure one of these engines could rev that high would be on a "spirited" shift meant for 3rd or 4th gear that ended up in 1st or 2nd respectively? It is my understanding that the rev limiter will kick in on the up-shift, but not the accidental down-shift? I'm just guessing though as I really don't know for sure.
I would tend to agree with this statement and know for a fact that this happens with great regularity in in toyota celica GTS and Acura cars with the 6 speed transmission.
I rebuilt a lot of engines (and transmissions) on cars where this happened and, the few that still ran, would have a "bouncy clutch pedal" because the spring tangs on the pressure plate had been bent from the event.
#55
04-03-2011, 08:28 AM
Join Date: Mar 2009
Location: Northern Virginia
Posts: 334
Rep Power: 48 The IMS is being sourced (used) by my shop... He should have it this coming week; I'll snap a pic up at the shop. My turbos are being sent out to Blouch tomorrow for a 20G upgrade. I'm going with a Clutchmasters Stage 3 (3900lb, Fibertough) setup... that should be ordered here soon (anyone else looking to go this route soon??? PM me!!!) The heads have already had a complete valve job (replaced 4 intake and 4 exhaust valves) and are due back in VA sometime this week. We will be doing some minor port work on the heads, but nothing major...
Now that I've got my head studs and rods in, the engine assembly should start within the next week or so. I'm also back in town from a month long trip, so I'll be able to better document the reassembly process!
I'm still a little uncertain on fuel delivery at this point, but am talking to a couple of people on my options and best route.
I don't recall if I mentioned this before, but this will be my 1st upgraded in a 2 stage process... I'll play around with this setup and whatever HP I can get out of it as it stands for a year or so... And then when I get bored with that, I'll go at it with one last push and do BIG turbos, big intercoolers, big fuel, blow-thru, etc... I'm sure this current jump from stock will have a big grin on my face for a good long while though.
Can't wait...
#56
04-03-2011, 02:58 PM
Very nice group of parts you got there..
Remember that the opposing cylinder on the porsche motor are at tdc and bdc at the same time. So bank1 cylinder 1 and bank two cylinder 4 go up and down at the same time, one on compression and the other on exhaust stroke. That makes some big drag. One more thing to ponder is that most blown stock motors have broken rod bolts. That means the rod came apart on the down stroke of the intake stroke. The down stroke of the compression stroke in the power stroke so the rod would bend not pull apart the rod bolts. I am a true believer in boatialing but not as shown in the video. I try to shape the bearing supports to guide the air into the adjacent cylinder and not into the crank were the opposing piston is trying to force air back at you.
Remember that the opposing cylinder on the porsche motor are at tdc and bdc at the same time. So bank1 cylinder 1 and bank two cylinder 4 go up and down at the same time, one on compression and the other on exhaust stroke. That makes some big drag. One more thing to ponder is that most blown stock motors have broken rod bolts. That means the rod came apart on the down stroke of the intake stroke. The down stroke of the compression stroke in the power stroke so the rod would bend not pull apart the rod bolts. I am a true believer in boatialing but not as shown in the video. I try to shape the bearing supports to guide the air into the adjacent cylinder and not into the crank were the opposing piston is trying to force air back at you.
Last edited by Tim941NYC; 04-03-2011 at 02:59 PM. Reason: spelling
#57
04-03-2011, 03:07 PM
Very nice group of parts you got there..
Remember that the opposing cylinder on the porsche motor are at tdc and bdc at the same time. So bank1 cylinder 1 and bank two cylinder 4 go up and down at the same time, one on compression and the other on exhaust stroke. That makes some big drag. One more thing to ponder is that most blown stock motors have broken rod bolts. That means the rod came apart on the down stroke of the intake stroke. The down stroke of the compression stroke in the power stroke so the rod would bend not pull apart the rod bolts. I am a true believer in boatialing but not as shown in the video. I try to shape the bearing supports to guide the air into the adjacent cylinder and not into the crank were the opposing piston is trying to force air back at you.
Remember that the opposing cylinder on the porsche motor are at tdc and bdc at the same time. So bank1 cylinder 1 and bank two cylinder 4 go up and down at the same time, one on compression and the other on exhaust stroke. That makes some big drag. One more thing to ponder is that most blown stock motors have broken rod bolts. That means the rod came apart on the down stroke of the intake stroke. The down stroke of the compression stroke in the power stroke so the rod would bend not pull apart the rod bolts. I am a true believer in boatialing but not as shown in the video. I try to shape the bearing supports to guide the air into the adjacent cylinder and not into the crank were the opposing piston is trying to force air back at you.
Tim, do you have any pics to show how you would do it?
Also, we are talking drag in static air chamber. Or do you mean that due to the pumping action within the opposing engine causes a rapid airflow internally? Is it internal air pressure within the block that increases this drag? I am not understanding this, sorry. Sometimes, these engines give me a headache
#58
04-03-2011, 03:40 PM
I scrapped all my broken cases and new to my smartphone's picture option! lol. The pumping action, but it is twice as much as you are used to seeing in a V or an inline motor. You have the volume of two cylinders get forced together, not just one. if the opposing cylinders were indexed on the same journal then the windage would be some what canceled by the volume not changes. The motor would not run so smooth like that though.
#59
04-04-2011, 05:51 AM
Join Date: Mar 2009
Location: Northern Virginia
Posts: 334
Rep Power: 48
I'm having a hard time visualizing this as well... And now I wonder how my shop is gonna cut up my block?
Can you draw up a detailed sketch on a ****tail napkin or something?
Can you draw up a detailed sketch on a ****tail napkin or something?
#60
04-04-2011, 07:58 AM
Where in N. Va are you located? I'm over in Arlington.