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Everything posted by JohnCh
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@CBuff I rotated your last photo. If you intended it to be upside down to highlight the effectiveness of the Schroths, please let me know and I'll return it to the original orientation
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Although expensive, I'm a fan of the Schroth Profi II with ASM. A danger of running a standard 4-point is that in a collision, the lap belt rides up the abdomen and can crush internal organs. Mounting the lap belt at the correct angle and using a crotch strap (5 or 6 point) keeps the lap belt in the correct position at the pelvis and minimizes this type of trauma. Schroth is the exception. Their ASM technology has a stitched fold on the inside shoulder belt that breaks in a collision, instantly lengthening that side and causing the lower body to slightly rotate. That rotation ensures the pelvis catches on top of the lap belt and prevents the belt from riding up to the soft tissue. They have crash test dummy videos that illustrate the difference. The Schroths also have a lot of flexibility in mounting; you can configure the lap belts as pull-up, or pull-down, or some combination, and there is also a decent amount of flexibility when placing the adjusting buckle location on the lap belt. This comes in handy if using one-piece seats like Tillets where the lap belt must thread through a hole in the side of the seat. I have them in the Caterham, Westfield, and Miata. No issues with fit in any of them.
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Hmm... Perhaps I should update my signature with this?
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Does this list only include paying jobs, or does volunteer work count? If the latter, then you forgot to add Vlad ego booster. It's right there in his signature
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I've seen various threads here over the years on the lack of performance shops that still rebuild/modify Zetecs. Esslinger Engineering, who has done Duratecs for a few of us, recently posted a photo on FB of a Zetec they are redoing. I pinged them to find out if this is a one-off or if Zetecs are in their wheelhouse, and was told they don't do many simply because of low demand, but they are happy to do more. Something to keep in mind, particularly for those in the Western US. https://esslingeracing.com/ -John
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But you don't have six two-seat road cars, so your excessiveness is manifested in a different way
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I thought I had a problem with owning impractical cars, but you have me beat. Next time someone asks me why I have five sportscars, rather than respond "because six would be excessive" I'll show them your post and explain I'm comparatively practical Very nice garage!
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The Regular Summary of Classified Ads of Se7ens Found For Sale
JohnCh replied to Croc's topic in Cars For Sale
Ignoring whether or not a new Caterham is worth the money at current prices, they are sufficiently expensive that a number of alternatives suddenly become realistic options for buyers. I'm curious if the really long waiting list is still a thing? I waited over 17 months after placing an order in 2021, but there have been at least two significant price increases since. -
The Regular Summary of Classified Ads of Se7ens Found For Sale
JohnCh replied to Croc's topic in Cars For Sale
A no-options 420S S3 is 42k GBP which is $53k at current exchange rates before you factor in shipping. In my case, that added $8k to the bill. Unless those prices have dropped considerably, even a stripper 420 is a $60k car delivered to the West Coast. Option up a 420R SV and it's not hard to cross into new Porsche Cayman territory. Things have changed. -
You might get more targeted answers if you update your profile with the type of se7en you own (it shows you are still looking). On my Westfield, I am using this model from Protex with the optional latching pins. Protex has a huge number of choices, and their latches are high quality. Unless you are okay drilling new holes, I'd pay attention to the mounting hole locations for your current latches. https://protex.com/27-1570MSZN-spring-claw-toggle-latch-with-safety-catch-light-duty-mild-steel-zinc-plate-passivate-silver-blue
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The Regular Summary of Classified Ads of Se7ens Found For Sale
JohnCh replied to Croc's topic in Cars For Sale
Superformance S1 located in OR: https://www.facebook.com/marketplace/item/1081099910487213/ -
What have I done? Two N00bs Try to Resurrect a 7
JohnCh replied to YourEconProf's topic in Build Threads
Hard to be certain from the video, but it looks like the outer MC has a lot more side-to-side room on the balance bar than the inner MC. What happens if you tighten that up? -
New Member: looking to build a 7 series 2 from scratch
JohnCh replied to Gordy's topic in General Sevens Discussion
Keith Tanner, the author of the GRM article, also wrote a book many years ago titled "How to Build a Cheap Sports Car" which is now out of print, but copies do come up on the used market occasionally. I'd spend time digging through his build diary here. It should help crystalize what's involved. https://cheapsportscar.net/diary.php?start=1 I'd also join https://www.locostusa.com/forums/ and https://locostbuilders.co.uk/forum/ if you haven't already done so. USA7s is not focused on any single brand, but the majority of owners have cars that started as kits from various companies such as Birkin, Caterham, Stalker, GBS, MK, WCM Ultralite, Westfield, etc. Although there are Locost owners here, and the requisite knowledge to build one among several of the members, you won't find as much on that topic as you will on those dedicated Locost forums. Belonging to all of the forums is a good approach, as-is digging through various build threads to see how some of the companies I mentioned above do it. At this point reading everything you can get your hands on will be helpful as you build your knowledge base and develop your build plan. I'm looking forward to hearing what you decide to do. Cheers John -
So, tell us a little about yourselves
JohnCh replied to slngsht's topic in General Sevens Discussion
Welcome @Cirving! For those interested, Cirving has also created a dedicated thread to his car. Turbocharged bike-engined se7en. Yeah, that's a sedate ride -
Hmm... perhaps @Croc should take a page from your playbook and use that for his new signature?
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Vlad, I misinterpreted your earlier comments and thought it was going back to full throttle that caused the problem, hence my earlier -- and incorrect -- comments about enrichment.
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I'm confused by the two statements above. Has this issue been there for years and the impetus to your initial troubleshooting, or is this more recent? @MV8 even if that portion of the map should be pulled up, would a change there (light-mid throttle and mid-high rpm) address the issue Vlad describes above and quoted below? Or Vlad are you saying it's after full throttle, then back on the throttle again, but not at full throttle? i.e. Full throttle > off throttle > light to mid throttle?
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This is key to understand. When did it start, when does it happen -- e.g. is it only when you describe it or are there other less severe issues that might be related? is it in specific rpm ranges? how sensitive is the severity of the issue to the load delta or rpm? -- and did anything else change leading up to the issue? Also, if it is as severe as you write, and you had a competent individual map the engine, then I would look towards mechanical or electrical issues. Could there be a wiring issue that is triggered from the movement of the engine when you suddenly back off like you describe? is there an issue with the injectors where they are not opening up as quickly as they should? is there a problem with the TPS that reacts badly to rapid movement? etc. As for the map changes fixing it, try visualizing where your throttle position and rpm are when this occurs and see if that is actually in the map range that you adjusted. If you were really going full throttle, then that is not an area of the map you touched.
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@Vovchandr Based on your description of the issue, I'm not sure that change should have made a difference. I'm curious to hear from people knowledgeable in this area, but it looks to me like that is the 3D graph which shows the amount of fuel injected (z-axis) at specific load (y-axis) and rpm (x-axis). The reason for the dip is that represents high rpm and low load. Sometimes volumetric efficiency is lower in those conditions, or fuel atomization is better, or it's tuned for fuel economy, or emissions, or it's largely ignored by the tuner, etc. The issue you describe -- hesitation or flat spot upon heavy throttle application -- points more towards enrichment settings. When you suddenly hit the throttle, the additional air in the cylinders occurs nearly instantaneously, but the fuel lags a step behind. To compensate for this, and to avoid a lean condition (your flat spot), additional fuel is momentarily added to the system until the fuel from the steady state map can catch up. It's possible that your map was overly lean in the area you increased and that conditions where you added throttle were such that you were staying in that portion of the map, but if you really are seeing it when going full throttle, then I suspect enrichment.
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It's muted by default. Try clicking the speaker icon on the top right.
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Under bonnet temps are pretty extreme for PLA or even PETG. Some of the major filament makers provide data sheets that include max temp ratings (claims?) before softening that are often helpful in filament selection. There are also some good YouTube channels that regularly test filaments to separate those claims from reality. If you haven't found this one, I highly recommend it. He has a PhD in Mechanical Engineering and teaches at the University of Budapest. His filament testing procedure reflects this background. https://www.youtube.com/@MyTechFun
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@fastg what filament did you use for the pulley?
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This forum has been strangely quiet given the number of people who 3D print, so let's start a thread for people to show their favorite print(s) they've made that's related to their passion for se7ens. The print doesn't need to be something you personally designed but should be a car part, tool, artwork or other related item you have printed. That means no searching on sites like Thingiverse and posting a bunch of things you think are interesting but have never tried. We can have a separate thread for that. Hopefully the items shown will give people ideas for their own projects. -John
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I moved this to General. The Fabrication section is for...fabrication.