engine rebuild and fuel economy mods

[bhearts]

i really like that you guys have so much engine building knowledge and supporting mods to boot. i have not even built my first engine yet at my tender age of 24. but ive seen the process and i thuroughly understand how engines work. the one thing that really gets me thinking the most about hp and fuel economy is header design. i love the look of somes beautiful flowing header. the problem with most headers (that ive seen) is that most if not almost all are designed for that racing peak torgue numbers. people want max flow at higher rpm levels. not to throw a rubber rooster at you guys...but the reason i wrote this thread was for fuel eco ideas. i want to develope max mpg for highway cruise without having to implement aero mods....who wants an even sillier looking aspire. this brings me back to my original point. could i design and build a header with smaller runners than customary to increase my peak torque numbers at cruise only. see, i have no reason to turn my car into a race car because i have a perfectly decent datsun just sitting around waiting for some sort of swap or turbo conversion. i have no idea the diameter or the exhaust ports on my b3 head. but i was planning on 1inch header primaries because it was smaller than what everyone else was running. somehow on a forum of one of the best fuel economy cars made in the last 25 years, we have closed our minds off to the idea of maybe lowering peak hp numbers for the ideas of better mpg.

let me also throw the idea of warm air intake out for everyone to chew on. this isnt a new idea by any means. but i live kansas. and it can get cold here in the winter. everyone knows cold air kills our little motors fuel atomization abilities which in turn hurts the main goal of my project. heres what i know about intakes. the general population upgrades to higher flowing air filters because it allows the motor to breathe easier. while there is nothing wrong with this - i dont not have any intentions to run my engine at wide open throttle at any time during my commute so the need for max air flow seems trivial by upgrading my filter only. but...with warmer air (then ambient) my throttle body would need to open up more than an ambient air build to take in the same amount of air to maintain cruise speeds. correct me if im wrong..but the air filter isnt the thing the limit the engines intake efficiency. its the throttle body. eliminating or getting close to eliminating this restriction would be the easiest way to maximize my breather at cruise. k and n claims 0-3 mpg increases from just a filter. imagine what you could gain from the thing that actually limits your air intake.

[blkfordsedan]

Yes, you could build a header specifically tuned for your application. Most aftermarket headers are designed to make the manufacturer max profit. Tube size, length and collector size are usually chosen by what is the easiest to make fit and cheapest to build and not what's optimum. The proper design can boost low end and probably increase MPG as well. As far as what that design is, you can do a Google search or there are books devoted to the subject.

[FestYboy]

i do believe that both Matt and Charlie have you pointed in the right direction, but you just havn't seen it yet.... the combustion event needs to become more efficient before anything else comes into play. you have to increase your BMEP, VE and BSFC (the last one actually had to drop). the end result should actually yeld higher HP and TQ numbers, not lower. the more efficient an engine is, the more power it will make.

[bhearts]

I stupidly feel sucked into a dumb conversation as scavenging & pulse velocity are directly related to port length & diameter, intake valve seat angle & header diameter & length & are manipulated by cam shaft overlap. Not only is this common knowledge, but a velocity probe on a flow bench confirms this. None of which are influenced by squish. Squish or quench influences full & air motion towards the center line of the chamber. The odd fact is, tightening the squish increases compression BUT reduces pre-ignition. For this reason, I have a proprietary process where I will spec a piston with a lower ring land location, run the piston crown above deck & machine the cylinder head with an appropriate recess which will allow the piston crown to enter the combustion chamber. Completely blocking the cylinder head gasket. Virtually eliminating head gasket failure in high cylinder pressure engines. The effect of squish has had ALOT of research around here. I happen to know that I am the only person to have done this.

doing this sounds amazing. id love to run a 13to1 1.3l. is there a proper name for this practice so i can locate more articles about it.

[bhearts]

but the more i think about it...this process sounds very expensive. have custom built pistons built and maybe even some special rods too. thats way outta my price range....but someone may prove me wrong. blkfordsedan was talking about using an mls headgasket on his 1.6l built but said it was gonna cost too much. stock head gaskets are what...like 35 bucks. i have no idea how much more a mls head gasket could cost. but if itd let me run uber high compression to increase my bmep and ve then i think itd be way worth it. where the heck do i find a mls gasket at? wait. let me check

[blkfordsedan]

A Cometic MLS gasket was about $100 for my B6....which was $99 more than I could afford right now. I don't believe they catalog one for a B3, but Cometic will make anything if you send them one to duplicate. The purpose in your application would only be to increase compression (and "squish" I guess). You don't need "über high compression".... that would only make it harder to live with and require more expensive fuel, which defeats the purpose. The way i see it, getting more air in the cylinders is just like adding more displacement. More air requires more fuel, so to me the objective would be to get the most energy out of the fuel that gets injected. Like FestyBoy said, More complete and efficient combustion and less loss through the driveline.

[bhearts]

i would love to mess around with some uber high compression. take full advantage of e85. or set up a system to use 80% pump gas and 20%methonal in a water meth injection system. in theory. if you have 80% of 87 octane fuel and 20% fuel that is 110 octane (methanols octane rating according to wikipedia), that comes out to an average octane rating of ((87x4)+(110x1))/5= 91 percent octane. which is a little lower than i was expecting...and i dont really know if you adjust octane ratings mixing for stoichiometric ratios. so i may just be blabbering about stuff thats socially not exceptable. but i do have full access to a station that has any mixes of ethanol from e30 to e85. and my roommate has a methanol buick park avenue. so he has a small farm of methanol that he buys from oklahoma city. so theres always that too. i know when he was tuning his buick up. he was running reliably at 20-1 AF with methanol at cruise. thats being read by a wideband o2 sensor and those are aleady adjusted by stoick ratios. i think....o no. im so confused.

[Movin]

Uber high compression..regardless of what that is will likely shorten the life of the engine unless an expensive and known to be reliable set of parts and knowledgeable fitting of those parts is purchased.

You may need to look at the budget and match that to a known successful combo.

Are you looking for lowest operating cost ? Or best mileage with a specific
fuel? Optimizing stock with parts like the custom headers, just for mileage?

[bhearts]

so lets imagine for a second that i could end up building a 11 to 1 compression b6 motor. you talk about the reliability of stock parts being an issue. if i was to minimize knock to that of a normal compression motor, and not run any boost through it...would anything really wear that much faster. pre ignition is what breaks motors, i cant really imagine a high compression jobber having any more issues that even a mildly boosted turbo motor. and turbo motor can be just as reliable as low comp n/a motors...right?

[bhearts]

my next 4 mods to my car are going to be a warm air intake, a stright water/steam injection system, plasti dipd stock aspire rims, and a custom built by me b3 header. im just trying to spark some big thinking here and to get everyone outside of their normal box of thinking. Iknow no one here is that interested in a straight fuel economy build. but id like to get some inputs on all my ideas before i go and throw things together. my biggest design thoughts is behind my 4 foot tri y header that im building. does anyone know the diameter of the b3 head exhaust ports. and can i make primaries smaller than this number if its over 1".?

[bhazard]

Re: engine rebuild and fuel economy mods

Import a B1.

[Damkid]

engine rebuild and fuel economy mods

Import a B1.

Yup