What has been common experience with NASCAR engines. Primarily 358ci R5P7 engines rated at approx 820 to 830hp. What is best use racing or exotic street? What had to be changed for either situation, cam/springs, oil pump/pan, compression, or what? Seems like excellent cost/hp from a fresh engine, worth it or too much hassle? What is going price for fresh engine, not asking but common buying price??

They make a nice engine for racing.
Buddy threw one in a 68 Dart( and it was a truck restrictor plate engine) only 12 to 1 with a “ dinky” 248/258 cam in it it.
Still ran low 9.40’s at 143 or so.
Requires some front end fab work to get it to fit, but there are adapter plates available to run a 904/727 behind them.
I dont think he had 10k in the complete motor

My Ex had a 98 Dakota with a R5P7 built by Eatmon , was sold as a 750 HP engine, had a wetsump pan, pump gas, ran a t56 behind it , went a best of 10.00, (atco in NJ) I forget the MPH on that run. the thing I hated about it it was very peaky on the street , didn't like pulling out at a light in traffic , I didn't like driving it, but at the track it was a lot of fun, I never went faster then a 10.80s in it. the EX put about 9500miles on it in the 5 years we were married , he freshened up the valves springs and clutch every spring but other then that maintenance it held up well. he pulled the R5P7 last year sold it and now is building a G3 Hemi for it.
http://www.eatmonraceparts.com/

The Honda 48mm (1.89") rod journal is a great idea for an engine never loaded at low RPM.
However, comparing it to a 2.375" (BBM) journal, the local oil pressure at the bearing surface is 20% lower at the same gauge pressure. The ratio of the journal circumferences determines the oil wedge viscosity, all the pump pressure does is "fill in the hole".
The difference decays as engine speed increases, and is harmless at power peak so a stronger relief spring won't help.
Needs thicker oil, larger pump, higher idle speed, and treat it like nitrous: no big power at low RPM.

I looked at this combo. Was for sale at a machine shop with engine dyno. It made over 800 HP. The power curve was not for drag racing unless you launched at 8000 and kept it the tight power bans. Definitely a cam change. Completely different mind/design set than the old purple stripe oval track cam. Roundy guy bought it before I could research any more.

My thought is that they would be tough to make work in a heavy, door slammer because of the narrow power band. They make big power at the rpm range they are designed to work at, but I don't think they make a lot of torque, and that big bore and short stroke would be tough to make work. I know some Pro Stick guys use them, but most of them don't run in a wide power band, they leave at a big rpm, and it doesn't vary much. You can buy them pretty reasonable, though, and I think it's limited application is why.

Dodge Dart, R5P7,>

https://www.youtube.com/watch?fbcli...o&v=nT3aBghw57k&feature=youtu.be

https://www.youtube.com/watch?v=MwY67JQ1w2k

I love 4 speed cars but they are a pain to maintain and race, especially ones like that one

If you are going to go down this road, buy complete.

A second hand engine will set you back around $6500+
Freshened engines tend to sell for $10-25K, depending on how many new parts are in it.

Spare parts aren't littered throughout eBay like they used to be though, so if building from parts, it get's quite expensive.

Interesting topic...there are quite a few of these over on racing junk...
https://www.racingjunk.com/Modern-H...acing-Ernie-Elliott-Dodge-R5-Engine.html

If I remember correctly the Ritter small block can be ordered to accept P7 heads. You could have a large displacement small block with the great flowing heads. Would that be an option?

I have a r5p7 that I put in a 69 dart with a g force 5 speed. The car has not made a pass with this engine yet. Biggest issue that I see for a true street car is the heads are so big for the cubic inch that the need rpm to make big power. The dart in the videos ran drag week in 2019 drove 1500+ miles and never even had the valve cover off.

There was a guy that ran one on Drag Week with a manual transmission who ran fairly well.

It was a nice car with some engine set back.

It was fast but not as fast as a Brett Miller W8 engine that one its class.

I like the telescopic steering on that Dart LOL!

there's a nice 454CI R5P7 for sale attaced is the Build sheet .

Biggest one I've seen was a 425ci , 4.224 bore and 3.795 stroke My uncle had it on the dyno at his old work , some where in the 900hp range 650 Tq ,

A local chassis builder and friend of mine put one in a light weight backhalf Duster years ago. It ran 5.40s in the 1/8 IIRC. I remember him talking about how they didn't do much to it except for a cam change (going off memory here) and it ran really well for what it was.