Search found 546 matches
- Tue Feb 20, 2024 5:40 pm
- Forum: Engine Tech
- Topic: camshaft intake valve closing
- Replies: 98
- Views: 4795
Re: camshaft intake valve closing
Have you got an engine simulator? Engine Analyzer by Performance Trends is a good place to start. The demo version locks you to a 302-HO with stock heads and no power adder, but you can still learn a ton. It can't give you degree by degree outputs like the more advanced ones can though.
- Tue Feb 20, 2024 1:19 am
- Forum: Engine Tech
- Topic: Mazda G6 2.6
- Replies: 5
- Views: 386
Re: Mazda G6 2.6
That exhaust manifold looks... easy to improve on. It's too large diameter for the power level, it looks like almost a 4-1 design (it's 4-2-1 I think, can't tell with the angle of photos, but the secondary is super short of it is part of the casting), and the merge angles are not good, especially on...
- Sun Feb 18, 2024 10:34 pm
- Forum: Engine Tech
- Topic: camshaft timing question
- Replies: 10
- Views: 685
Re: camshaft timing question
It's also worth noting that on vvt engines maximum power is usually a minimum overlap position. Why? Because the IVC is so late and with the fixed cam duration late IVC is more important than overlap at the top end. The range of IVC close options can be as much as 50 degrees... Of course both is bes...
- Sun Feb 18, 2024 3:12 am
- Forum: Engine Tech
- Topic: NHRA STOCK valve job
- Replies: 52
- Views: 6164
Re: NHRA STOCK valve job
That almost makes it seem like you could have an arbitrary number of cuts extending to 90 degrees in the port and even up to chamber clearancing, as long as the tool you used rotated 360 degrees around the valve guide axis. "Yeah my 17 angle seat is 35mm wide, extends to the bore, and actually ...
- Wed Feb 14, 2024 9:36 pm
- Forum: Engine Tech
- Topic: Maximum Velocity at Valve Seat
- Replies: 17
- Views: 810
Re: Maximum Velocity at Valve Seat
I've seen someone (DV?) suggest that efficiencies over 1 are due to the venturi effect creating a greater depression at the seat itself than the vacuum motor is generating and if we were to measure depression at the seat the numbers would make more sense.
- Tue Feb 13, 2024 10:37 pm
- Forum: Engine Tech
- Topic: What breaks rockers? (OHC hydraulic roller)
- Replies: 5
- Views: 391
What breaks rockers? (OHC hydraulic roller)
Thinking about the Ford OHC Intech 6 (precursor to the Barra), accepted wisdom is that the stock rockers break between 6500 and 7500 rpm. But there's not really any concrete information on why, what else is going on, and if it can be avoided. The rockers are cast (can't recall the material), roller ...
- Thu Feb 01, 2024 7:15 am
- Forum: Engine Tech
- Topic: Billet Block internal heater - worth it?
- Replies: 23
- Views: 2108
Re: Billet Block internal heater - worth it?
This seems like a good use for exhaust heat. Could you adapt an egr cooler to run oil through it (or a short coolant passage that also runs through a coolant oil "cooler") and block it off once the oil approaches operating temperature? Getting pre-turbo gas (say from the external wastegate...
- Tue Jan 23, 2024 4:30 pm
- Forum: Engine Tech
- Topic: the art of a valve job
- Replies: 44
- Views: 5931
Re: the art of a valve job
My 2 cents worth would be that if whichever valve you want to talk about. ( INT or EXH or both ) is not sealing due to thermal conditions that just can not be simulated in a static way, then the best flowing valve job is a waste of time to include in the conversation. That sounds like a job for a t...
- Tue Jan 23, 2024 12:30 am
- Forum: Engine Tech
- Topic: Bill Jones books ISBN
- Replies: 20
- Views: 2132
Re: Bill Jones books ISBN
If he publishes them to the right format at a place that prints on demand (like Amazon does iirc) we can just buy new copies on demand without the need for a traditional publisher and print run
- Thu Jan 18, 2024 2:59 am
- Forum: Engine Tech
- Topic: Valve seat profiles
- Replies: 1
- Views: 614
Re: Valve seat profiles
Makes sense. There's not a lot of uniformity of flow around the seat and often you don't even want that (case in point, tumble. You deliberately don't want short side flow in some head designs), so why should seats be symmetrical? The only production thing I know of that could even use a whole valve...
- Sat Jan 13, 2024 3:13 am
- Forum: Engine Tech
- Topic: How much swirl is too much swirl
- Replies: 75
- Views: 276515
Re: How much swirl is too much swirl
To increase tumble you can focus flow on the long side filling in the roof to give a straight shot at the edge of the valve, and if you're game deliberately block short side flow. Toyota did this with their "dynamic force" engine series. I mean it wasn't the only change, but it was the maj...
- Fri Jan 12, 2024 7:02 am
- Forum: Engine Tech
- Topic: Quick and dirty grudge.
- Replies: 23
- Views: 37771
Re: Quick and dirty grudge.
I still vote for turbocharging what you've got and giving it sexy ferrari noises. Don't tell him what's in it.
- Sun Jan 07, 2024 2:51 pm
- Forum: Engine Tech
- Topic: Using PCV for crankcase vacuum on a street car?
- Replies: 11
- Views: 53657
Re: Using PCV for crankcase vacuum on a street car?
If you built a system that had two check valves made from a piece of plastic and 1" plastic ball bearing, with breather filters on top, then yes.
What pcv valve were you running on that? I'm concerned that a stock one will open immediately at full throttle and I'll lose the vacuum that way
What pcv valve were you running on that? I'm concerned that a stock one will open immediately at full throttle and I'll lose the vacuum that way
- Sat Jan 06, 2024 9:46 pm
- Forum: Engine Tech
- Topic: Using PCV for crankcase vacuum on a street car?
- Replies: 11
- Views: 53657
Re: Using PCV for crankcase vacuum on a street car?
That's why I still wanted to use the pcv, so it's still got more or less expected "leak" around the throttle. Just use a pressure reducing valve on the crankcase inlet.
- Sat Jan 06, 2024 5:23 pm
- Forum: Engine Tech
- Topic: Using PCV for crankcase vacuum on a street car?
- Replies: 11
- Views: 53657
Re: Using PCV for crankcase vacuum on a street car?
Well I'm at 240k km / 150k miles, there's almost certainly not perfect ring sealing going on. I expect the pcv valve itself would be part of not holding a vacuum though (attempting to open at low manifold vacuum). Any ideas on if that's actually a thing and/or how do I stop it from losing the vacuum...