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02-13-2018, 02:21 PM | #1 |
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Is building a motor necessary for FI on this motor?
Cliff Notes below... I like to ramble...
I like to plan in advance. I have been deciding on a FI kit since I bought my car in 2015. This wasn't easy because I needed something that is CARB approved, and I am picky about presentation. It is not like I need something for winning a show, but I can't just throw a FI kit in the engine bay, even if it will rarely be seen. My OCD doesn't allow it. Ironically, I don't mind if the car's paint isn't perfect or if the car needs washing; I like to use my cars and small imperfections add character and patina, but the engine bay can't look like a shit show. This motor doesn't lend itself to a gorgeous engine bay (former MKIV turbo owner). In NA form, it would need a trick, Porsche-Singer-like manifold or their velocity stacks to look good: https://car-images.bauersecure.com/p...=90&scale=down http://www.seriouswheels.com/pics-20...2-1280x960.jpg In FI form, the turbos or centrifugal SCs seem to be put wherever they can fit. Often this leaves the engine bay looking crowded and a mess. I know most don't care, but I do. I never had a V8 Muscle car, just not my thing (I never tried them though, so maybe it could be my thing lol, and I do give props though to the new batch of American muscle cars, which do look more appealing than those of old), so I don't know if I would like a positive displacement SC (feels like a big engine) compared to a turbo or centrifugal SC (if anyone in the area feels so kinda as to give me a ride, so I can test them out, shoot me a PM; it would be greatly appreciated). I would love a turbo because I like turbo build and the sounds, but I am not a fan of the Works kit. Props to them for making a great, CARB kit. If it had a FMIC instead of the top mount then I think the layout could be agreeable to my senses (maybe), but my other gripe is that they had to do the turbo off the mid pipe. Maybe response isn't terrible, but I would have to imagine there is a decent delay. The cleanest SC kits are the Edelbrock and Harrop, visually. The Harrop looks the best IMO. The manifold sits lower than the Edelbrock's, and it looks OEM or also like a V6 is sitting under the hood, so I have decided to get the Harrop kit once they get CARB approved. But I can't stand the water lines, so my plan is to weld up some coolant pipes like how OEMs do it, and I will run the pipes close to the engine for a cleaner look. Getting to the meet and potatoes finally... Do I build the motor or not? I'm done with the days of having a cop pop my hood and being sighted for an illegally modified motor, and I don't want to have to do significant modifications every two years to pass smog. With that said, it would be appealing to run duel tunes (CARB for smog, if that is necessary, if they can tell, and a custom/DT tune) that takes power slightly beyond what a CARB tune normally puts down. My goals would depend on how much power I want, and I won't know that until I have it, but I don't think I would want a lot like greater than 400whp. I live in Northern California, so all we have is crap 91 octane. The closest E85 is 27 miles away in Napa. Even if I had E85, I don't know if it can be run stealthy (is that a word?). It is a shame because E85 seems like the perfect choice; I get more power, and E85 protects the motor. Since running E85 100% of the time isn't a viable option (and because removing the FlexFuel kit might be a hassle, or is it simple?), my other choice is to build the motor. The question is, do many blow their motors on CARB kits such that a built motor is necessary, or is it only necessary for horsepower beyond a certain threshold like 300whp? I know Edelbrock has a warranty for the motor on their CARB tune, so I would imagine blown motors on CARB kits are a rarity. But running 12.5:1 compression on a FI motor seems like insanity without E85. I know everyone says the motor is weak, that the rods are crap, but I have a feeling that no rods are strong enough to deal with significant preignition, and there is a recipe for disaster, for just that, with a high compression motor and FI, so my next question is: for those who have built their motor, did you go with stiffer components or did you also drop compression? I was thinking of building the motor with 10.0:1 compression if I would build the motor. This would allow me to run on 91 octane safely, I think. For my modest power goals, I could do rods and low-compression pistons and that would probably be it. For my power goals, I don't think the heads would need porting, right, it probably flows enough? Is it worth it to build the heads with stiffer springs and light weight components? Will that raise the revs, not raise the revs enough to be worth the cost, be safer for normal revs, or be overkill? For now, the car is my daily (I don't commute more than five to ten miles a day to work or the gym, but I am more of a drive it like I stole it driver), and I occasionally use it for cannon carving when I am not on my motorcycle. I would like to expand to autocross and tracking the car, but realistically only a few times a year. Thanks if you made it this far. CLIFF NOTES: -Wants to get the Harrop kit when it is CARB approved. Wants legal looking setup. -Doesn't have access to E85 to run it daily. Could run it sometimes. -1st question: Is removing or installing a flex fuel kit simple for smog? -2nd question: Does the motor need to be built for CARB kits on 91 octane, or for the extra power from running E85 with a second tune on the CARB pulley? -Doesn't believe the motor is safe with FI running 12.5:1 without E85. -3rd question: Did people build their motor with stiffer components and lower compression or just stiffer components? -4th question: Is it worth it to build the head for my power goals? Will that enhance the safety enough to justify the cost? |
02-13-2018, 02:40 PM | #2 |
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No need to build the engine with a Harrop setup, especially if you are sticking to carb-legal/91...
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02-13-2018, 02:42 PM | #3 |
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1) Assuming you have access to your carb tune, removing a flex fuel kit is not complicated.
2)For a carb tune, the tune is optimized for the stock motor. Building your motor might mess up the carb tune. At that point, re-tuning your car for the built motor would be more ideal. **It is not necessary to build your motor for a carb tune / carb power level. 3) Compression ratio depends on power level and fuel availability. For a supercharger, you will make more power with higher compression; assuming you have fuel that can support your power level. 4) No it is not necessary for your power goals. I have met people who built their motor for more power and blew it a week later. Building a motor / head does not guarantee a safety factor.
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02-13-2018, 02:54 PM | #4 | |
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With EcuTek you can have 4 maps available for instant switching using the cruise control stalk. The E85 kit, with an appropriate non-E85 tune (either pre-loaded or ready to flash) would take about 15 mins at most to remove. Two quick connect fuel lines, unplug the harness, change tune. Done. Remove components (1 bolt, 2 screws and some velcro for the control module) if the smog guy gives you guff. I have 12000 miles on a completely stock 2017 motor with zero issues. I drive hard and to redline a few times every trip and commute. I have read something about NOT reducing the compression on a built motor because of the way direct injection works on a thermal/chemical level, but have not researched it..so take that FWIW. Also keep in mind, a built motor will not be CARB compliant - which you stated as one of your goals. (I'm assuming your really only worried about the visual inspection) If you have never driven both turbo and positive displacement cars, then you need to. They drive very different. Unless your OCD on engine asthetics over-powers your driving enjoyment, then carry on. I also like the look of a boxer more than inline or vee motors. Very function over-form looking that appeals to me. Easy to work on too. Me and my brother installed the Harrop and Flexfuel kit in about 6 hours, with a few breaks. It's basically like changing the intake manifold and radiator in one job. |
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02-13-2018, 05:13 PM | #5 |
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Building the engine is a bit of a conundrum for me. It's cheaper to build it while you have a good core to resell, but hopefully you can keep boost reasonable and things work out and you never needed the build in the first place. Either way, it's good to have your complete engine build plans and $$$ ready to go in case it doesn't work out.
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02-13-2018, 06:13 PM | #6 |
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Have you considered the Vortech? They're based out of CA.
IMHO it's the best looking system and would pass for OEM. CARB legal too. https://vortechsuperchargers.com/pro...-brz-tuner-kit The Eldebrock is a good looking kit. TBH, I would eliminate the Harrop unless they have local support. I don't know if they do or not. |
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02-13-2018, 06:52 PM | #7 |
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I think harrop has local support with The Racer's Line.
Cosworth has also done a lot of R&D to ensure the longevity of the engine. They went as far as to measure the pressure in each cylinder and then tailored their tune for that. @Matt@Cosworth could give some feedback on their findings with the motor. I believe the recommend not to exceed 290 horsepower at the crank. Though many have done it anyway.
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02-13-2018, 07:36 PM | #8 | |
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02-13-2018, 08:56 PM | #9 | |
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Neal over at the racers line uses a Harrop on one of his track cars. To the OP: Definetly send Neal an email at neal@theracersline.com. He is hands down one of the most (if not the most) qualified mechanics in our area for FI as he has installed more kits than anyone. He is also the only NorCal approved Edelbrock installer (that i'm aware of). He also doesnt charge an arm and a leg for install either (assuming you wouldnt do it yourself).
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02-14-2018, 12:27 AM | #10 |
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Thanks for all the replies.
On 91 octane, for major production cars, I think the highest factory compression ratio for a FI motor is 10.5:1, and apparently that is pretty high. Motors like the Evo are around 9. They make up for it with high amount of boost, but this is safer than less boost and higher compression. It may also be better for turbo efficiency. But to focus on that first point, how can the 86 with a 12.5:1 compression survive at all with boost on pump gas? Thinking of Boyles Law, my basic understanding says that compressing air can be much more dangerous than adding more air. Because pressure builds exponentially as volume decreases, compressing the volume a lot can result in huge buildups of pressure, but adding more gas to a larger volume won't add exponential pressure: For that graph, going from a volume of 15 to 10 units meant a 20% increase in pressure from 100 to 120 units, a change of 20 units, yet going the same five units from 45 to 40 seems to only change the pressure from 30 to 35 units, maybe less than that. Depending on what the curve for an engine looks like, a change from 12.5:1 compression to 13.5:1 or to 11.5:1 could be a much greater pressure differential than a 9.0:1 going to 10.0:1 or 8.0:1. It seems reasonable to guess that maybe, just maybe, that the reason this engine is known for being so "weak" has more to do with the high compression ratio, which is fine for being NA, but is just a ticking, time bomb for FI. This also explains why some people seem to be lucky and others are not. Perhaps it takes the right conditions to cause a large knock or preignition. Altitude, ambient temperature, quality of the fuel and heat on the motor all influence the possibility of a knock that could be severe enough to bend a rod. Some pump gas is 91 and some is 93. Some might have 10% ethanol, but others might have 15%. There are so many factors, but if the motor is 12.5:1 and FI then the opportunities for some people based on where they live and how they drive could be multiplied. Just saying it is possible. Regardless, it sounds like I will be fine going with a CARB tune on a stock motor. @PhyrraM ...I would definitely like to try a ride in a positive displacement SC, and a centrifugal SC, and a turbo car too, but I don't think that is going to happen unless someone local offers me a ride. My intuition says that immediate throttle response is what fits the light, sharp and nimble 86's personality. For a daily, this seems best too. If this car turns into a stripped-down, trailered, track car one day then I would likely change to a turbo. @new2subaru ...I agree, the Vortech SC is the most OEM looking centrifugal SC, but I still like a more compact setup. @Xxyion ...I will most likely be buying the SC kit through Racersline. I am a DIYer, but if it comes to it, I have heard nothing but good things about Neal, and I won't be afraid to give him a call. Last edited by Irace86.2.0; 02-14-2018 at 01:39 AM. |
02-14-2018, 01:41 AM | #11 | |
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and you might be onto something except...
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No, instead, the most likely culprit is a lack of proper quality control on the rods. There are some exceptionally weak rods coming through on some of these engines and THAT is the crap shoot and why some cars can be fine at close to 400whp and some fail completely stock. Jaden |
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02-14-2018, 03:39 AM | #12 |
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The AVO turbo kit looks extremely stock. The only thing is it doesn't come with a CARB legal tune.
300whp is actually quite a bit for this platform. And 400whp is just plain scary in terms of how quick it is. Try riding in a local's boosted twin and you'll quickly find out that 300whp is more than enough. You shouldn't need to build the engine to run a carb legal tune. And even with e85, you shouldn't need to build the engine and you'd still be hitting 350whp easy. Have you considered water and meth? It doesn't really get talked about too much on these forums, but it is another alternative to run more boost.
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02-14-2018, 09:53 AM | #13 | |
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02-14-2018, 10:46 AM | #14 | |
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The DCR is dictating cylinder pressure. Variable camshaft = variable DCR, fixed camshaft = fixed DCR. And then you have DFI aiding with more precise placement, timing, and metering of fuel. |
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