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Search found 2989 matches

by David Redszus
Fri Sep 25, 2020 7:13 pm
Forum: Engine Tech
Topic: intake texturing alcohol fuel
Replies: 13
Views: 396

Re: intake texturing alcohol fuel

If surface texturing actually works, then we have the task of determining just how rough the surface should actually be. And under what conditions, i.e. air temperature, barometric pressure, fuel water content, etc. If the fuel mass delivery remains unchanged (same jets) and a performance improvemen...
by David Redszus
Fri Sep 25, 2020 2:03 pm
Forum: Engine Tech
Topic: intake texturing alcohol fuel
Replies: 13
Views: 396

Re: intake texturing alcohol fuel

In the past lots of discussion about the benefits of texturing intake manifolds and runners. From my experience it seems to work, with gasoline as the fuel. I did not see much on texturing when using alcohol as fuel. Since the fuels have different evaporation rates, does anybody have experience wit...
by David Redszus
Wed Sep 23, 2020 11:20 pm
Forum: Engine Tech
Topic: Diesel fuel in a FI gas motor = more power?
Replies: 14
Views: 2250

Re: Diesel fuel in a FI gas motor = more power?

Gasoline has ~ 125,000 BTU / gal Diesel ~ 138,000 BTU / gal Kerosene ~ 135,000 BTU / gal The above comparisons are invalid. The heating values are based on BTU/gal (volume), while engines run on fuel mass. The reason that diesel seems more potent is that a gallon of diesel weighs more than a gallon...
by David Redszus
Wed Sep 23, 2020 10:59 am
Forum: Engine Tech
Topic: Are clearances actually tighter now?
Replies: 22
Views: 962

Re: Are clearances actually tighter now?

Modern engines are built with more accuracy. Engine designers consider dynamic clearances which includes factors such as component flex, thermal expansion, stacking tolerances, and a lot more. That is quite different than merely considering cold static clearances. While clearances are up to the engi...
by David Redszus
Tue Sep 22, 2020 11:51 am
Forum: Engine Tech
Topic: MPFI with 16 injectors
Replies: 11
Views: 284

Re: MPFI with 16 injectors

Two injectors per cylinder have been used quite successfully for many years. They were used on the Mercedes DTM engines and are currently being used on turbo Yamaha drag snowmobile engines. Ditto for Formula One engines as well. If high fuel flow is required, twin injectors solve several problems. T...
by David Redszus
Sat Sep 19, 2020 6:06 pm
Forum: Engine Tech
Topic: How narrow can you run an intake seat ?
Replies: 6
Views: 636

Re: How narrow can you run an intake seat ?

I have an issue with intake valves hitting the bore wall. I would like to make the last race meeting of the year (no time to do a new head). I was wondering whether I could turn down the valve diameter which would obviously narrow down the inlet seat. I figure that if I reduce the intake seat to .0...
by David Redszus
Fri Sep 18, 2020 11:43 am
Forum: Engine Tech
Topic: Specific Torque
Replies: 13
Views: 626

Re: Specific Torque

A calculation of Specific Torque, while useful, does not consider the effect of engine speed. The method used to compare the state of tune of various engines is to normalize for engine size and engine speed. The calculated value is called Brake Mean Effective Pressure (BMEP). It reflects the average...
by David Redszus
Wed Sep 16, 2020 12:02 pm
Forum: Engine Tech
Topic: Throttle response EFI: TBI vs. MPFI on 800 hp BBC
Replies: 6
Views: 203

Re: Throttle response EFI: TBI vs. MPFI on 800 hp B....BC

Throttle response is often a debatable issue with little supporting evidence. So I pulled up some engine data from a port injected Porsche running at Road America. Two sets of data are shown. In a 2:30 lap, coming off a corner, the data does not repeat consistently. Time.Sec...Throttle %.....Lambda....
by David Redszus
Tue Sep 15, 2020 9:48 pm
Forum: Engine Tech
Topic: Cam lobe decel ramp - valve life?
Replies: 32
Views: 1372

Re: Cam lobe decel ramp - valve life?

Following is Cam Dr data for an exhaust closing ramp showing cam angle, velocity (in/deg), velocity (in/sec), and valve spring seat force. Cam...Lift....Velocity....Velocity....Springforce angle..in......in/deg......in/sec......lbs 65....0.05332.....7.170....129.1.......127.7 67....0.03994.....6.160...
by David Redszus
Tue Sep 15, 2020 5:01 pm
Forum: Engine Tech
Topic: Cam intake lobe vs exhaust lobe
Replies: 11
Views: 1510

Re: Cam intake lobe vs exhaust lobe

#1 reason why intake and exhaust lobes match: it's the cheapest way to make the cam . The intake and exhaust ports have completely different functions, and what happens in each has almost no similarities (except gas volume). You raise an important point that should be considered. The intake and exh...
by David Redszus
Wed Sep 09, 2020 5:54 pm
Forum: Engine Tech
Topic: Exhaust flames - running lean or just high temp?
Replies: 13
Views: 742

Re: Exhaust flames - running lean or just high temp?

This YouTube vid of a burnout car, note how there’s flames continually exiting the end of the pipes even though the pipes are perhaps 2-1/2 metres long. At idle, yeah, okay, it’s just unburnt fuel catching alight as it hits the atmosphere, but what about when it’s going full noise? Does the type of...
by David Redszus
Tue Sep 08, 2020 11:36 pm
Forum: Engine Tech
Topic: Cam lobe decel ramp - valve life?
Replies: 32
Views: 1372

Re: Cam lobe decel ramp - valve life?

No answers to my question about recommended max seating velocity limit values. The factors affecting valve seating wear are not related to valve velocity . They are a function of valve acceleration which will impart a force to the valve greater than the resisting spring. This sometimes occurs at th...
by David Redszus
Tue Sep 08, 2020 4:35 pm
Forum: Engine Tech
Topic: Watered gas.
Replies: 17
Views: 551

Re: Watered gas.

Use a siphon tube with the pick up end about 1" from the bottom of the container.

Adding ethanol or methanol does not remove water. They both simply absorb the water which is 100% soluble in either alcohol.
by David Redszus
Fri Sep 04, 2020 12:22 am
Forum: Engine Tech
Topic: using SF Air Turbine to determine Header problems
Replies: 36
Views: 1292

Re: using SF Air Turbine to determine Header problems

"the EGT is the System's Speed ( Speed of Sound FPS ) you have to work with, and the "Timing" of the returning negative pressure Wave @ TDC-Overlap is where huge amount of TQ and HP gains are, so the earlier EVO event is ... the longer the Primary Tubes need to be . How did you determine exhaust ga...
by David Redszus
Wed Sep 02, 2020 11:55 am
Forum: Engine Tech
Topic: E85 testing
Replies: 15
Views: 399

Re: E85 testing

Rule #1 for oxygenated fuels: the indicated oxygenated value is NEVER correct. The alcohol content of E85 will vary from E70 to E90, depending on season and location. More alcohol is used during warm months to deal with pre-ignition and detonation; less is used during cold months to assist with col...